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Full vulnerability report · 2026
CVE-2026-74632High confidence

mm/huge_memory: fix huge_zero_pfn race

Linux · Linux

7.8HighCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 252 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Medium, lowered one band.downgradedsince 25 Aug 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.13% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Linux Linux and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 252 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

25 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 20 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.12.105-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.1.187-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcelinux-6.12Vendor fix publishedDebian records a fixed source-package version for this release.6.12.107-1~deb12u1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.7.1.9-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.7.1.9-1Debian Security Tracker ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinuxAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-awsAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azureAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azure-fdeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azure-nvidiaAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gcpAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gkeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gkeopAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-ibmAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-lowlatencyAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidiaAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidia-lowlatencyAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidia-tegraAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-oem-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-oracleAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-raspiAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-raspi-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-riscvAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-xilinxAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical Ubuntu Security ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-74632 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitykernel: mm/huge_memory: fix huge_zero_pfn race
232 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • kernel as a component of Red Hat Enterprise Linux 10
  • kernel-64k as a component of Red Hat Enterprise Linux 10
  • kernel-64k-core as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10
  • kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10
  • kernel-64k-devel as a component of Red Hat Enterprise Linux 10
  • kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10
Summary
A flaw was found in the Linux kernel's memory management (mm/huge_memory). A race condition can occur between a memory shrinker and a concurrent page fault when handling huge zero pages. This race can lead to the `huge_zero_pfn` being incorrectly set, causing the huge zero page to be misidentified as an ordinary Transparent Huge Page (THP) folio. Consequently, the huge zero page may be incorrectly split or otherwise mishandled, potentially leading to system instability or unexpected memory behavior.
Remediation
Fix deferred
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-64569

No EUVD known-exploited evidence

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix huge_zero_pfn race Patch series "mm/huge_memory: fix huge_zero_pfn race", v2. There is a subtle race in the reference-counted huge_zero_folio implementation. The fast path atomic logic fails to account for the fact that the shrinker (which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a racing get_huge_zero_folio() installed a valid value there. This results in huge_zero_folio being correctly set but huge_zero_pfn being set incorrectly and thus is_huge_zero_pfn() and consequently is_huge_zero_pmd() will misidentify the huge zero folio as being an ordinary THP folio. This can result in the huge zero folio being split and otherwise treated incorrectly. The solution to this is very subtle as there is an atomic fast path, and thus ordering in weakly ordered architectures has to be treated very carefully. The first commit fixes the issue by introducing a spinlock around huge_zero_[pfn, folio, refcount] write, with careful consideration paid to load/store ordering in the fast path. It is placed first and kept as small as possible so that it can be backported on its own. The second commit is a pure cleanup which reworks the CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent logic from the dynamically allocated one. This patch (of 2): If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted by huge_zero_refcount and returned by mm_get_huge_zero_folio(). When the caller is done with the huge zero page, its reference count is decremented. Only a shrinker can set the reference count to zero. A race can unfortunately occur between a shrinker decrementing the reference count to zero and a concurrent page fault. This is because shrink_huge_zero_folio_scan() might, if very unlucky, be preempted between setting huge_zero_refcount to zero and writing an invalid value. During this time get_huge_zero_folio() could write to huge_zero_pfn before shrink_huge_zero_folio_scan() resumes. In this event the huge zero folio will be persistently misidentified causing the THP code path to be entered inappropriately for the huge zero folio: CPU 0 CPU 1 =======================================|================================= shrink_huge_zero_folio_scan() | atomic_cmpxchg() sets refcount to 0 | xchg() sets huge_zero_folio to NULL | get_huge_zero_folio() | | atomic_inc_not_zero() -> zero preempted for a long time | Allocate new huge zero folio | | Write valid huge_zero_folio v | Write valid huge_zero_pfn Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite! This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly returning false for a huge zero page which could result in issues like the huge zero folio being incorrectly split. Note that the issue is with huge_zero_pfn not huge_zero_folio, as get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set huge_zero_folio. Fix the issue by introducing a spinlock, huge_zero_lock, to prevent concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount. There needs to be significant care taken here to ensure correctness: The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which is outside of the critical section, and means huge zero allocation is gated on zero huge_zero_refcount. The fast path doesn't use huge_zero_lock, so the critical section is irrelevant to it. So invariants are required - huge_zero_refcount MUST: * Only be set in the huge_zero_lock critical section to ensure serialisation of huge_zero_pfn, huge_zero_folio and ---truncated---

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
7.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 252 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix huge_zero_pfn race Patch series "mm/huge_memory: fix huge_zero_pfn race", v2. There is a subtle race in the reference-counted huge_zero_folio implementation. The fast path atomic logic fails to account for the fact that the shrinker (which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a racing get_huge_zero_folio() installed a valid value there. This results in huge_zero_folio being correctly set but huge_zero_pfn being set incorrectly and thus is_huge_zero_pfn() and consequently is_huge_zero_pmd() will misidentify the huge zero folio as being an ordinary THP folio. This can result in the huge zero folio being split and otherwise treated incorrectly. The solution to this is very subtle as there is an atomic fast path, and thus ordering in weakly ordered architectures has to be treated very carefully. The first commit fixes the issue by introducing a spinlock around huge_zero_[pfn, folio, refcount] write, with careful consideration paid to load/store ordering in the fast path. It is placed first and kept as small as possible so that it can be backported on its own. The second commit is a pure cleanup which reworks the CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent logic from the dynamically allocated one. This patch (of 2): If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted by huge_zero_refcount and returned by mm_get_huge_zero_folio(). When the caller is done with the huge zero page, its reference count is decremented. Only a shrinker can set the reference count to zero. A race can unfortunately occur between a shrinker decrementing the reference count to zero and a concurrent page fault. This is because shrink_huge_zero_folio_scan() might, if very unlucky, be preempted between setting huge_zero_refcount to zero and writing an invalid value. During this time get_huge_zero_folio() could write to huge_zero_pfn before shrink_huge_zero_folio_scan() resumes. In this event the huge zero folio will be persistently misidentified causing the THP code path to be entered inappropriately for the huge zero folio: CPU 0 CPU 1 =======================================|================================= shrink_huge_zero_folio_scan() | atomic_cmpxchg() sets refcount to 0 | xchg() sets huge_zero_folio to NULL | get_huge_zero_folio() | | atomic_inc_not_zero() -> zero preempted for a long time | Allocate new huge zero folio | | Write valid huge_zero_folio v | Write valid huge_zero_pfn Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite! This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly returning false for a huge zero page which could result in issues like the huge zero folio being incorrectly split. Note that the issue is with huge_zero_pfn not huge_zero_folio, as get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set huge_zero_folio. Fix the issue by introducing a spinlock, huge_zero_lock, to prevent concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount. There needs to be significant care taken here to ensure correctness: The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which is outside of the critical section, and means huge zero allocation is gated on zero huge_zero_refcount. The fast path doesn't use huge_zero_lock, so the critical section is irrelevant to it. So invariants are required - huge_zero_refcount MUST: * Only be set in the huge_zero_lock critical section to ensure serialisation of huge_zero_pfn, huge_zero_folio and ---truncated---

What

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix huge_zero_pfn race Patch series "mm/huge_memory: fix huge_zero_pfn race", v2. There is a subtle race in the reference-counted huge_zero_folio implementation. The fast path atomic logic fails to account for the fact that the shrinker (which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a racing get_huge_zero_folio() installed a valid value there. This results in huge_zero_folio being correctly set but huge_zero_pfn being set incorrectly and thus is_huge_zero_pfn() and consequently is_huge_zero_pmd() will misidentify the huge zero folio as being an ordinary THP folio. This can result in the huge zero folio being split and otherwise treated incorrectly. The solution to this is very subtle as there is an atomic fast path, and thus ordering in weakly ordered architectures has to be treated very carefully. The first commit fixes the issue by introducing a spinlock around huge_zero_[pfn, folio, refcount] write, with careful consideration paid to load/store ordering in the fast path. It is placed first and kept as small as possible so that it can be backported on its own. The second commit is a pure cleanup which reworks the CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent logic from the dynamically allocated one. This patch (of 2): If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted by huge_zero_refcount and returned by mm_get_huge_zero_folio(). When the caller is done with the huge zero page, its reference count is decremented. Only a shrinker can set the reference count to zero. A race can unfortunately occur between a shrinker decrementing the reference count to zero and a concurrent page fault. This is because shrink_huge_zero_folio_scan() might, if very unlucky, be preempted between setting huge_zero_refcount to zero and writing an invalid value. During this time get_huge_zero_folio() could write to huge_zero_pfn before shrink_huge_zero_folio_scan() resumes. In this event the huge zero folio will be persistently misidentified causing the THP code path to be entered inappropriately for the huge zero folio: CPU 0 CPU 1 =======================================|================================= shrink_huge_zero_folio_scan() | atomic_cmpxchg() sets refcount to 0 | xchg() sets huge_zero_folio to NULL | get_huge_zero_folio() | | atomic_inc_not_zero() -> zero preempted for a long time | Allocate new huge zero folio | | Write valid huge_zero_folio v | Write valid huge_zero_pfn Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite! This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly returning false for a huge zero page which could result in issues like the huge zero folio being incorrectly split. Note that the issue is with huge_zero_pfn not huge_zero_folio, as get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set huge_zero_folio. Fix the issue by introducing a spinlock, huge_zero_lock, to prevent concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount. There needs to be significant care taken here to ensure correctness: The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which is outside of the critical section, and means huge zero allocation is gated on zero huge_zero_refcount. The fast path doesn't use huge_zero_lock, so the critical section is irrelevant to it. So invariants are required - huge_zero_refcount MUST: * Only be set in the huge_zero_lock critical section to ensure serialisation of huge_zero_pfn, huge_zero_folio and ---truncated---

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix huge_zero_pfn race Patch series "mm/huge_memory: fix huge_zero_pfn race", v2. There is a subtle race in the reference-counted huge_zero_folio implementation. The fast path atomic logic fails to account for the fact that the shrinker (which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a racing get_huge_zero_folio() installed a valid value there. This results in huge_zero_folio being correctly set but huge_zero_pfn being set incorrectly and thus is_huge_zero_pfn() and consequently is_huge_zero_pmd() will misidentify the huge zero folio as being an ordinary THP folio. This can result in the huge zero folio being split and otherwise treated incorrectly. The solution to this is very subtle as there is an atomic fast path, and thus ordering in weakly ordered architectures has to be treated very carefully. The first commit fixes the issue by introducing a spinlock around huge_zero_[pfn, folio, refcount] write, with careful consideration paid to load/store ordering in the fast path. It is placed first and kept as small as possible so that it can be backported on its own. The second commit is a pure cleanup which reworks the CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent logic from the dynamically allocated one. This patch (of 2): If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted by huge_zero_refcount and returned by mm_get_huge_zero_folio(). When the caller is done with the huge zero page, its reference count is decremented. Only a shrinker can set the reference count to zero. A race can unfortunately occur between a shrinker decrementing the reference count to zero and a concurrent page fault. This is because shrink_huge_zero_folio_scan() might, if very unlucky, be preempted between setting huge_zero_refcount to zero and writing an invalid value. During this time get_huge_zero_folio() could write to huge_zero_pfn before shrink_huge_zero_folio_scan() resumes. In this event the huge zero folio will be persistently misidentified causing the THP code path to be entered inappropriately for the huge zero folio: CPU 0 CPU 1 =======================================|================================= shrink_huge_zero_folio_scan() | atomic_cmpxchg() sets refcount to 0 | xchg() sets huge_zero_folio to NULL | get_huge_zero_folio() | | atomic_inc_not_zero() -> zero preempted for a long time | Allocate new huge zero folio | | Write valid huge_zero_folio v | Write valid huge_zero_pfn Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite! This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly returning false for a huge zero page which could result in issues like the huge zero folio being incorrectly split. Note that the issue is with huge_zero_pfn not huge_zero_folio, as get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set huge_zero_folio. Fix the issue by introducing a spinlock, huge_zero_lock, to prevent concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount. There needs to be significant care taken here to ensure correctness: The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which is outside of the critical section, and means huge zero allocation is gated on zero huge_zero_refcount. The fast path doesn't use huge_zero_lock, so the critical section is irrelevant to it. So invariants are required - huge_zero_refcount MUST: * Only be set in the huge_zero_lock critical section to ensure serialisation of huge_zero_pfn, huge_zero_folio and ---truncated---

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration.
CWE not yet assigned
CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-64569Official EUVD mapping

In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix huge_zero_pfn race Patch series "mm/huge_memory: fix huge_zero_pfn race", v2. There is a subtle race in the reference-counted huge_zero_folio implementation. The fast path atomic logic fails to account for the fact that the shrinker (which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a racing get_huge_zero_folio() installed a valid value there. This results in huge_zero_folio being correctly set but huge_zero_pfn being set incorrectly and thus is_huge_zero_pfn() and consequently is_huge_zero_pmd() will misidentify the huge zero folio as being an ordinary THP folio. This can result in the huge zero folio being split and otherwise treated incorrectly. The solution to this is very subtle as there is an atomic fast path, and thus ordering in weakly ordered architectures has to be treated very carefully. The first commit fixes the issue by introducing a spinlock around huge_zero_[pfn, folio, refcount] write, with careful consideration paid to load/store ordering in the fast path. It is placed first and kept as small as possible so that it can be backported on its own. The second commit is a pure cleanup which reworks the CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent logic from the dynamically allocated one. This patch (of 2): If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted by huge_zero_refcount and returned by mm_get_huge_zero_folio(). When the caller is done with the huge zero page, its reference count is decremented. Only a shrinker can set the reference count to zero. A race can unfortunately occur between a shrinker decrementing the reference count to zero and a concurrent page fault. This is because shrink_huge_zero_folio_scan() might, if very unlucky, be preempted between setting huge_zero_refcount to zero and writing an invalid value. During this time get_huge_zero_folio() could write to huge_zero_pfn before shrink_huge_zero_folio_scan() resumes. In this event the huge zero folio will be persistently misidentified causing the THP code path to be entered inappropriately for the huge zero folio: CPU 0 CPU 1 =======================================|================================= shrink_huge_zero_folio_scan() | atomic_cmpxchg() sets refcount to 0 | xchg() sets huge_zero_folio to NULL | get_huge_zero_folio() | | atomic_inc_not_zero() -> zero preempted for a long time | Allocate new huge zero folio | | Write valid huge_zero_folio v | Write valid huge_zero_pfn Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite! This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly returning false for a huge zero page which could result in issues like the huge zero folio being incorrectly split. Note that the issue is with huge_zero_pfn not huge_zero_folio, as get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set huge_zero_folio. Fix the issue by introducing a spinlock, huge_zero_lock, to prevent concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount. There needs to be significant care taken here to ensure correctness: The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which is outside of the critical section, and means huge zero allocation is gated on zero huge_zero_refcount. The fast path doesn't use huge_zero_lock, so the critical section is irrelevant to it. So invariants are required - huge_zero_refcount MUST: * Only be set in the huge_zero_lock critical section to ensure serialisation of huge_zero_pfn, huge_zero_folio and ---truncated---

Official EUVD record ↗
BSI · German · WID-SEC-2026-2970Linux Kernel: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen, möglicherweise Sicherheitsmaßnahmen zu umgehen, einen Denial-of-Service-Zustand herbeizuführen oder vertrauliche Informationen offenzulegen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260826Security Bulletin 26 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 26 Aug 2026, published on 26 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1232Multiples vulnérabilités dans le noyau Linux de Debian LTS

d?id=CVE-2026-74621 Référence CVE CVE-2026-74622 https://www.cve.org/CVERecord?id=CVE-2026-74622 Référence CVE CVE-2026-74623 https://www.cve.org/CVERecord?id=CVE-2026-74623 Référence CVE CVE-2026-74624 https://www.cve.org/CVERecord?id=CVE-2026-74624 Référence CVE CVE-2026-74625 https://www.cve.org/CVERecord?id=CVE-2026-74625 Référence CVE CVE-2026-74626 https://www.cve.org/CVERecord?id=CVE-2026-74626 Référence CVE CVE-2026-74628 https://www.cve.org/CVERecord?id=CVE-2026-74628 Référence CVE CVE-2026-74630 https://www.cve.org/CVERecord?id=CVE-2026-74630 Référence CVE CVE-2026-74631 https://www.cve.org/CVERecord?id=CVE-2026-74631 Référence CVE CVE-2026-74632 https://www.cve.org/CVERecord?id=CVE-2026-74632 Référence CVE CVE-2026-74634 https://www.cve.org/CVERecord?id=CVE-2026-74634 Référence CVE CVE-2026-74635 https://www.cve.org/CVERecord?id=CVE-2026-74635 Référence CVE CVE-2026-74636 https://www.cve.org/CVERecord?id=CVE-2026-74636 Référence CVE CVE-2026-74637 https://www.cve.org/CVERecord?id=CVE-2026-74637 Référence CVE CVE-2026-74641 https://www.cve.org/CVERecord?id=CVE-2026-74641 Référence CVE CVE-2026-74644 https://www.cve.org/CVERecord?id=CVE-2026-74644 Référence CVE CVE-2026-74646 https://www.cve.org/CVERecord?id=CVE-2026-74646 Référence CVE CVE-2026-74647 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1163Multiples vulnérabilités dans le noyau Linux de Debian LTS

d?id=CVE-2026-74621 Référence CVE CVE-2026-74622 https://www.cve.org/CVERecord?id=CVE-2026-74622 Référence CVE CVE-2026-74623 https://www.cve.org/CVERecord?id=CVE-2026-74623 Référence CVE CVE-2026-74624 https://www.cve.org/CVERecord?id=CVE-2026-74624 Référence CVE CVE-2026-74625 https://www.cve.org/CVERecord?id=CVE-2026-74625 Référence CVE CVE-2026-74626 https://www.cve.org/CVERecord?id=CVE-2026-74626 Référence CVE CVE-2026-74628 https://www.cve.org/CVERecord?id=CVE-2026-74628 Référence CVE CVE-2026-74630 https://www.cve.org/CVERecord?id=CVE-2026-74630 Référence CVE CVE-2026-74631 https://www.cve.org/CVERecord?id=CVE-2026-74631 Référence CVE CVE-2026-74632 https://www.cve.org/CVERecord?id=CVE-2026-74632 Référence CVE CVE-2026-74635 https://www.cve.org/CVERecord?id=CVE-2026-74635 Référence CVE CVE-2026-74636 https://www.cve.org/CVERecord?id=CVE-2026-74636 Référence CVE CVE-2026-74637 https://www.cve.org/CVERecord?id=CVE-2026-74637 Référence CVE CVE-2026-74641 https://www.cve.org/CVERecord?id=CVE-2026-74641 Référence CVE CVE-2026-74647 https://www.cve.org/CVERecord?id=CVE-2026-74647 Référence CVE CVE-2026-74648 https://www.cve.org/CVERecord?id=CVE-2026-74648 Référence CVE CVE-2026-74649 https://www.cve.org/CVERecord?id=CVE-2026-74649 Référence CVE CVE-2026-74650 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1090Multiples vulnérabilités dans le noyau Linux de Debian

d?id=CVE-2026-74620 Référence CVE CVE-2026-74621 https://www.cve.org/CVERecord?id=CVE-2026-74621 Référence CVE CVE-2026-74622 https://www.cve.org/CVERecord?id=CVE-2026-74622 Référence CVE CVE-2026-74623 https://www.cve.org/CVERecord?id=CVE-2026-74623 Référence CVE CVE-2026-74624 https://www.cve.org/CVERecord?id=CVE-2026-74624 Référence CVE CVE-2026-74625 https://www.cve.org/CVERecord?id=CVE-2026-74625 Référence CVE CVE-2026-74628 https://www.cve.org/CVERecord?id=CVE-2026-74628 Référence CVE CVE-2026-74630 https://www.cve.org/CVERecord?id=CVE-2026-74630 Référence CVE CVE-2026-74631 https://www.cve.org/CVERecord?id=CVE-2026-74631 Référence CVE CVE-2026-74632 https://www.cve.org/CVERecord?id=CVE-2026-74632 Référence CVE CVE-2026-74634 https://www.cve.org/CVERecord?id=CVE-2026-74634 Référence CVE CVE-2026-74635 https://www.cve.org/CVERecord?id=CVE-2026-74635 Référence CVE CVE-2026-74636 https://www.cve.org/CVERecord?id=CVE-2026-74636 Référence CVE CVE-2026-74637 https://www.cve.org/CVERecord?id=CVE-2026-74637 Référence CVE CVE-2026-74641 https://www.cve.org/CVERecord?id=CVE-2026-74641 Référence CVE CVE-2026-74644 https://www.cve.org/CVERecord?id=CVE-2026-74644 Référence CVE CVE-2026-74646 https://www.cve.org/CVERecord?id=CVE-2026-74646 Référence CVE CVE-2026-74647 https://www.cve.org/CVERecord?id=

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
Linux: < 5.13, 5.10.267 ≤ 5.10.*, 5.15.218 ≤ 5.15.*, 6.1.184 ≤ 6.1.*, 6.6.153 ≤ 6.6.*, 6.12.104 ≤ 6.12.*, 6.18.45 ≤ 6.18.*, 7.1.9 ≤ 7.1.*, 7.2 ≤ *
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 22 Aug 2026 · Last source change 27 Aug 2026, 12:39 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-23
European sourceENISA EUVD · EUVD-2026-64569
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceUnavailable
NVD statusNVD received

Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added remediation: git.kernel.org/9c0fd1802ce06d7709f0bae4edeb085288f28764; removed remediation: git.kernel.org/9332b080ad57650d1dc582e54517f9fc78ef89cc.
    Before
    remediation: git.kernel.org/9332b080ad57650d1dc582e54517f9fc78ef89cc
    After
    remediation: git.kernel.org/9c0fd1802ce06d7709f0bae4edeb085288f28764
    CNA ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    3b77e8c8cde581dadab9a0f1543a347e24315f11 < 9332b080ad57650d1dc582e54517f9fc78ef89cc; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < f3a874a903053c53fb53ba287ea9eacda69c68e8; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 6024f6d0d9b9ca5138bfc4ac6f6e4bdf616e42b3; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 105d04edbec83010df5728f74d17fd9c108e7553; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < ab7e4b407c7f58d1a003134eff3841f303d5ccc2; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 33192a26cddea7a7e4ca66e5c3eebd36fa8be2bb; fc1fbc5b017b6f5ef24a4a93f33cd022225e01c8; bd092a0f19423d7e9e81182314a96ecd6a14f3b7 · Fixed: < 5.13; 6.1.184 ≤ 6.1.*; 6.6.153 ≤ 6.6.*; 6.12.104 ≤ 6.12.*; 6.18.45 ≤ 6.18.*; 7.1.9 ≤ 7.1.*; 7.2 ≤ *
    After
    6527d8ef68c3ca3c455e38ae2a37cd7810caec73 < 9c0fd1802ce06d7709f0bae4edeb085288f28764; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < b7041ba61c5da4e0b56f9be58cfb87d7689724e4; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 9332b080ad57650d1dc582e54517f9fc78ef89cc; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < f3a874a903053c53fb53ba287ea9eacda69c68e8; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 6024f6d0d9b9ca5138bfc4ac6f6e4bdf616e42b3; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 105d04edbec83010df5728f74d17fd9c108e7553; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < ab7e4b407c7f58d1a003134eff3841f303d5ccc2; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 33192a26cddea7a7e4ca66e5c3eebd36fa8be2bb · Fixed: < 5.13; 5.10.267 ≤ 5.10.*; 5.15.218 ≤ 5.15.*; 6.1.184 ≤ 6.1.*; 6.6.153 ≤ 6.6.*; 6.12.104 ≤ 6.12.*; 6.18.45 ≤ 6.18.*; 7.1.9 ≤ 7.1.*
    CNA ↗
  3. SeveritySeverity changed from Unknown to High.
    Before
    Unknown
    After
    High
    CNA ↗
  4. CVSS scoreCVSS score changed from not recorded to 7.8 (CVSS 3.1 · CNA · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
    Before
    not recorded
    After
    7.8 (CVSS 3.1 · CNA · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
    CNA ↗
  5. Vendor guidanceAuthoritative vendor guidance changed: added remediation: git.kernel.org/9332b080ad57650d1dc582e54517f9fc78ef89cc; removed remediation: git.kernel.org/6024f6d0d9b9ca5138bfc4ac6f6e4bdf616e42b3.
    Before
    remediation: git.kernel.org/6024f6d0d9b9ca5138bfc4ac6f6e4bdf616e42b3
    After
    remediation: git.kernel.org/9332b080ad57650d1dc582e54517f9fc78ef89cc
    CNA ↗
  6. Affected versionsThe structured affected or fixed version information changed.
    Before
    3b77e8c8cde581dadab9a0f1543a347e24315f11 < 6024f6d0d9b9ca5138bfc4ac6f6e4bdf616e42b3; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 105d04edbec83010df5728f74d17fd9c108e7553; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < ab7e4b407c7f58d1a003134eff3841f303d5ccc2; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 33192a26cddea7a7e4ca66e5c3eebd36fa8be2bb; fc1fbc5b017b6f5ef24a4a93f33cd022225e01c8; bd092a0f19423d7e9e81182314a96ecd6a14f3b7; 6527d8ef68c3ca3c455e38ae2a37cd7810caec73; b1daf8f862136894a4595770a44e4508808fb806 · Fixed: < 5.13; 6.12.104 ≤ 6.12.*; 6.18.45 ≤ 6.18.*; 7.1.9 ≤ 7.1.*; 7.2 ≤ *
    After
    3b77e8c8cde581dadab9a0f1543a347e24315f11 < 9332b080ad57650d1dc582e54517f9fc78ef89cc; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < f3a874a903053c53fb53ba287ea9eacda69c68e8; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 6024f6d0d9b9ca5138bfc4ac6f6e4bdf616e42b3; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 105d04edbec83010df5728f74d17fd9c108e7553; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < ab7e4b407c7f58d1a003134eff3841f303d5ccc2; 3b77e8c8cde581dadab9a0f1543a347e24315f11 < 33192a26cddea7a7e4ca66e5c3eebd36fa8be2bb; fc1fbc5b017b6f5ef24a4a93f33cd022225e01c8; bd092a0f19423d7e9e81182314a96ecd6a14f3b7 · Fixed: < 5.13; 6.1.184 ≤ 6.1.*; 6.6.153 ≤ 6.6.*; 6.12.104 ≤ 6.12.*; 6.18.45 ≤ 6.18.*; 7.1.9 ≤ 7.1.*; 7.2 ≤ *
    CNA ↗
  7. ENISA EUVD mappingEUVD-2026-64569 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-64569"}
    ENISA EUVD ↗
  8. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-64569↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-74632 · cve.blacktree.nl