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Full vulnerability report · 2026
CVE-2026-43420High confidence

ceph: fix i_nlink underrun during async unlink

Linux · Linux

4.7MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 20 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 severityMediumOperational priority:Low, lowered one band.downgradedsince 11 May 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.11% 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: No default targetRemediation target: Normal maintenance

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 20 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.

24 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.6.12.85-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.1.170-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.19.10-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcelinuxVendor fix publishedDebian records a fixed source-package version for this release.6.19.10-1Debian Security Tracker ↗Source updated 6 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
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-2026-28726

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 20 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: ceph: fix i_nlink underrun during async unlink During async unlink, we drop the `i_nlink` counter before we receive the completion (that will eventually update the `i_nlink`) because "we assume that the unlink will succeed". That is not a bad idea, but it races against deletions by other clients (or against the completion of our own unlink) and can lead to an underrun which emits a WARNING like this one: WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 Modules linked in: CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drop_nlink+0x50/0x68 lr : ceph_unlink+0x6c4/0x720 sp : ffff80012173bc90 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8 Call trace: drop_nlink+0x50/0x68 (P) vfs_unlink+0xb0/0x2e8 do_unlinkat+0x204/0x288 __arm64_sys_unlinkat+0x3c/0x80 invoke_syscall.constprop.0+0x54/0xe8 do_el0_svc+0xa4/0xc8 el0_svc+0x18/0x58 el0t_64_sync_handler+0x104/0x130 el0t_64_sync+0x154/0x158 In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion. Meanwhile, between this call and the following drop_nlink() call, a worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own completion). These will lead to a set_nlink() call, updating the `i_nlink` counter to the value received from the MDS. If that new `i_nlink` value happens to be zero, it is illegal to decrement it further. But that is exactly what ceph_unlink() will do then. The WARNING can be reproduced this way: 1. Force async unlink; only the async code path is affected. Having no real clue about Ceph internals, I was unable to find out why the MDS wouldn't give me the "Fxr" capabilities, so I patched get_caps_for_async_unlink() to always succeed. (Note that the WARNING dump above was found on an unpatched kernel, without this kludge - this is not a theoretical bug.) 2. Add a sleep call after ceph_mdsc_submit_request() so the unlink completion gets handled by a worker thread before drop_nlink() is called. This guarantees that the `i_nlink` is already zero before drop_nlink() runs. The solution is to skip the counter decrement when it is already zero, but doing so without a lock is still racy (TOCTOU). Since ceph_fill_inode() and handle_cap_grant() both hold the `ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this seems like the proper lock to protect the `i_nlink` updates. I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using `afs_vnode.cb_lock`). All three have the zero check as well.

What

In the Linux kernel, the following vulnerability has been resolved: ceph: fix i_nlink underrun during async unlink During async unlink, we drop the `i_nlink` counter before we receive the completion (that will eventually update the `i_nlink`) because "we assume that the unlink will succeed". That is not a bad idea, but it races against deletions by other clients (or against the completion of our own unlink) and can lead to an underrun which emits a WARNING like this one: WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 Modules linked in: CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drop_nlink+0x50/0x68 lr : ceph_unlink+0x6c4/0x720 sp : ffff80012173bc90 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8 Call trace: drop_nlink+0x50/0x68 (P) vfs_unlink+0xb0/0x2e8 do_unlinkat+0x204/0x288 __arm64_sys_unlinkat+0x3c/0x80 invoke_syscall.constprop.0+0x54/0xe8 do_el0_svc+0xa4/0xc8 el0_svc+0x18/0x58 el0t_64_sync_handler+0x104/0x130 el0t_64_sync+0x154/0x158 In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion. Meanwhile, between this call and the following drop_nlink() call, a worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own completion). These will lead to a set_nlink() call, updating the `i_nlink` counter to the value received from the MDS. If that new `i_nlink` value happens to be zero, it is illegal to decrement it further. But that is exactly what ceph_unlink() will do then. The WARNING can be reproduced this way: 1. Force async unlink; only the async code path is affected. Having no real clue about Ceph internals, I was unable to find out why the MDS wouldn't give me the "Fxr" capabilities, so I patched get_caps_for_async_unlink() to always succeed. (Note that the WARNING dump above was found on an unpatched kernel, without this kludge - this is not a theoretical bug.) 2. Add a sleep call after ceph_mdsc_submit_request() so the unlink completion gets handled by a worker thread before drop_nlink() is called. This guarantees that the `i_nlink` is already zero before drop_nlink() runs. The solution is to skip the counter decrement when it is already zero, but doing so without a lock is still racy (TOCTOU). Since ceph_fill_inode() and handle_cap_grant() both hold the `ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this seems like the proper lock to protect the `i_nlink` updates. I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using `afs_vnode.cb_lock`). All three have the zero check as well.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

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: ceph: fix i_nlink underrun during async unlink During async unlink, we drop the `i_nlink` counter before we receive the completion (that will eventually update the `i_nlink`) because "we assume that the unlink will succeed". That is not a bad idea, but it races against deletions by other clients (or against the completion of our own unlink) and can lead to an underrun which emits a WARNING like this one: WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 Modules linked in: CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655 Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drop_nlink+0x50/0x68 lr : ceph_unlink+0x6c4/0x720 sp : ffff80012173bc90 x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680 x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647 x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203 x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365 x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74 x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94 x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002 x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8 Call trace: drop_nlink+0x50/0x68 (P) vfs_unlink+0xb0/0x2e8 do_unlinkat+0x204/0x288 __arm64_sys_unlinkat+0x3c/0x80 invoke_syscall.constprop.0+0x54/0xe8 do_el0_svc+0xa4/0xc8 el0_svc+0x18/0x58 el0t_64_sync_handler+0x104/0x130 el0t_64_sync+0x154/0x158 In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion. Meanwhile, between this call and the following drop_nlink() call, a worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own completion). These will lead to a set_nlink() call, updating the `i_nlink` counter to the value received from the MDS. If that new `i_nlink` value happens to be zero, it is illegal to decrement it further. But that is exactly what ceph_unlink() will do then. The WARNING can be reproduced this way: 1. Force async unlink; only the async code path is affected. Having no real clue about Ceph internals, I was unable to find out why the MDS wouldn't give me the "Fxr" capabilities, so I patched get_caps_for_async_unlink() to always succeed. (Note that the WARNING dump above was found on an unpatched kernel, without this kludge - this is not a theoretical bug.) 2. Add a sleep call after ceph_mdsc_submit_request() so the unlink completion gets handled by a worker thread before drop_nlink() is called. This guarantees that the `i_nlink` is already zero before drop_nlink() runs. The solution is to skip the counter decrement when it is already zero, but doing so without a lock is still racy (TOCTOU). Since ceph_fill_inode() and handle_cap_grant() both hold the `ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this seems like the proper lock to protect the `i_nlink` updates. I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using `afs_vnode.cb_lock`). All three have the zero check as well.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

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 → Time-of-check Time-of-use (TOCTOU) Race Condition → 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
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-367 ↗

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

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:H/PR:L/UI:N/S:U/C:N/I:N/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.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.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.
CWE-367
A

Official authority intelligence

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

BSI · German · WID-SEC-2026-1454Linux Kernel: Mehrere Schwachstellen

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

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1229Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43373 Référence CVE CVE-2026-43378 https://www.cve.org/CVERecord?id=CVE-2026-43378 Référence CVE CVE-2026-43380 https://www.cve.org/CVERecord?id=CVE-2026-43380 Référence CVE CVE-2026-43381 https://www.cve.org/CVERecord?id=CVE-2026-43381 Référence CVE CVE-2026-43382 https://www.cve.org/CVERecord?id=CVE-2026-43382 Référence CVE CVE-2026-43386 https://www.cve.org/CVERecord?id=CVE-2026-43386 Référence CVE CVE-2026-43387 https://www.cve.org/CVERecord?id=CVE-2026-43387 Référence CVE CVE-2026-43405 https://www.cve.org/CVERecord?id=CVE-2026-43405 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=CVE-2026-43430 Référence CVE CVE-2026-43432 https://www.cve.org/CVERecord?id=CVE-2026-43432 Référence CVE CVE-2026-43439 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1093Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43380 Référence CVE CVE-2026-43381 https://www.cve.org/CVERecord?id=CVE-2026-43381 Référence CVE CVE-2026-43382 https://www.cve.org/CVERecord?id=CVE-2026-43382 Référence CVE CVE-2026-43386 https://www.cve.org/CVERecord?id=CVE-2026-43386 Référence CVE CVE-2026-43387 https://www.cve.org/CVERecord?id=CVE-2026-43387 Référence CVE CVE-2026-43405 https://www.cve.org/CVERecord?id=CVE-2026-43405 Référence CVE CVE-2026-43406 https://www.cve.org/CVERecord?id=CVE-2026-43406 Référence CVE CVE-2026-43407 https://www.cve.org/CVERecord?id=CVE-2026-43407 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=CVE-2026-43430 Référence CVE CVE-2026-43432 https://www.cve.org/CVERecord?id=CVE-2026-43432 Référence CVE CVE-2026-43439 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1066Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43397 Référence CVE CVE-2026-43405 https://www.cve.org/CVERecord?id=CVE-2026-43405 Référence CVE CVE-2026-43408 https://www.cve.org/CVERecord?id=CVE-2026-43408 Référence CVE CVE-2026-43409 https://www.cve.org/CVERecord?id=CVE-2026-43409 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43412 https://www.cve.org/CVERecord?id=CVE-2026-43412 Référence CVE CVE-2026-43413 https://www.cve.org/CVERecord?id=CVE-2026-43413 Référence CVE CVE-2026-43415 https://www.cve.org/CVERecord?id=CVE-2026-43415 Référence CVE CVE-2026-43419 https://www.cve.org/CVERecord?id=CVE-2026-43419 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43421 https://www.cve.org/CVERecord?id=CVE-2026-43421 Référence CVE CVE-2026-43424 https://www.cve.org/CVERecord?id=CVE-2026-43424 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0985Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43370 Référence CVE CVE-2026-43373 https://www.cve.org/CVERecord?id=CVE-2026-43373 Référence CVE CVE-2026-43380 https://www.cve.org/CVERecord?id=CVE-2026-43380 Référence CVE CVE-2026-43381 https://www.cve.org/CVERecord?id=CVE-2026-43381 Référence CVE CVE-2026-43382 https://www.cve.org/CVERecord?id=CVE-2026-43382 Référence CVE CVE-2026-43386 https://www.cve.org/CVERecord?id=CVE-2026-43386 Référence CVE CVE-2026-43387 https://www.cve.org/CVERecord?id=CVE-2026-43387 Référence CVE CVE-2026-43405 https://www.cve.org/CVERecord?id=CVE-2026-43405 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=CVE-2026-43430 Référence CVE CVE-2026-43432 https://www.cve.org/CVERecord?id=CVE-2026-43432 Référence CVE CVE-2026-43439 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0954Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43407 Référence CVE CVE-2026-43408 https://www.cve.org/CVERecord?id=CVE-2026-43408 Référence CVE CVE-2026-43409 https://www.cve.org/CVERecord?id=CVE-2026-43409 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43412 https://www.cve.org/CVERecord?id=CVE-2026-43412 Référence CVE CVE-2026-43413 https://www.cve.org/CVERecord?id=CVE-2026-43413 Référence CVE CVE-2026-43414 https://www.cve.org/CVERecord?id=CVE-2026-43414 Référence CVE CVE-2026-43415 https://www.cve.org/CVERecord?id=CVE-2026-43415 Référence CVE CVE-2026-43419 https://www.cve.org/CVERecord?id=CVE-2026-43419 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43421 https://www.cve.org/CVERecord?id=CVE-2026-43421 Référence CVE CVE-2026-43424 https://www.cve.org/CVERecord?id=CVE-2026-43424 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0926Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43407 Référence CVE CVE-2026-43408 https://www.cve.org/CVERecord?id=CVE-2026-43408 Référence CVE CVE-2026-43409 https://www.cve.org/CVERecord?id=CVE-2026-43409 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43412 https://www.cve.org/CVERecord?id=CVE-2026-43412 Référence CVE CVE-2026-43413 https://www.cve.org/CVERecord?id=CVE-2026-43413 Référence CVE CVE-2026-43414 https://www.cve.org/CVERecord?id=CVE-2026-43414 Référence CVE CVE-2026-43415 https://www.cve.org/CVERecord?id=CVE-2026-43415 Référence CVE CVE-2026-43419 https://www.cve.org/CVERecord?id=CVE-2026-43419 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43421 https://www.cve.org/CVERecord?id=CVE-2026-43421 Référence CVE CVE-2026-43424 https://www.cve.org/CVERecord?id=CVE-2026-43424 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0864Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2026-43360 Référence CVE CVE-2026-43361 https://www.cve.org/CVERecord?id=CVE-2026-43361 Référence CVE CVE-2026-43362 https://www.cve.org/CVERecord?id=CVE-2026-43362 Référence CVE CVE-2026-43405 https://www.cve.org/CVERecord?id=CVE-2026-43405 Référence CVE CVE-2026-43406 https://www.cve.org/CVERecord?id=CVE-2026-43406 Référence CVE CVE-2026-43407 https://www.cve.org/CVERecord?id=CVE-2026-43407 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43413 https://www.cve.org/CVERecord?id=CVE-2026-43413 Référence CVE CVE-2026-43414 https://www.cve.org/CVERecord?id=CVE-2026-43414 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43455 https://www.cve.org/CVERecord?id=CVE-2026-43455 Référence CVE CVE-2026-43456 https://www.cve.org/CVERecord?id=CVE-2026-43456 Référence CVE CVE-2026-43469 https://www.cve.org/CVERecord?id=CVE-2026-43469 Référence CVE CVE-2026-43470 https://www.cve.org/CVERecord?id=CVE-2026-43470 Référence CVE CVE-2026-43472 https://www.cve.org/CVERecord?id=CVE-2026-43472 Référence CVE CVE-2026-43483 https://www.cve.org/CVERecord?id=CVE-2026-43483 Référence CVE CVE-2026-43491 https://www.cve.org/CVERecord?id=CVE-2026-43491 Référence CVE CVE-2026-43492 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0696Multiples vulnérabilités dans le noyau Linux de Debian LTS

d?id=CVE-2026-43370 Référence CVE CVE-2026-43373 https://www.cve.org/CVERecord?id=CVE-2026-43373 Référence CVE CVE-2026-43381 https://www.cve.org/CVERecord?id=CVE-2026-43381 Référence CVE CVE-2026-43382 https://www.cve.org/CVERecord?id=CVE-2026-43382 Référence CVE CVE-2026-43383 https://www.cve.org/CVERecord?id=CVE-2026-43383 Référence CVE CVE-2026-43386 https://www.cve.org/CVERecord?id=CVE-2026-43386 Référence CVE CVE-2026-43387 https://www.cve.org/CVERecord?id=CVE-2026-43387 Référence CVE CVE-2026-43407 https://www.cve.org/CVERecord?id=CVE-2026-43407 Référence CVE CVE-2026-43411 https://www.cve.org/CVERecord?id=CVE-2026-43411 Référence CVE CVE-2026-43420 https://www.cve.org/CVERecord?id=CVE-2026-43420 Référence CVE CVE-2026-43424 https://www.cve.org/CVERecord?id=CVE-2026-43424 Référence CVE CVE-2026-43425 https://www.cve.org/CVERecord?id=CVE-2026-43425 Référence CVE CVE-2026-43426 https://www.cve.org/CVERecord?id=CVE-2026-43426 Référence CVE CVE-2026-43427 https://www.cve.org/CVERecord?id=CVE-2026-43427 Référence CVE CVE-2026-43428 https://www.cve.org/CVERecord?id=CVE-2026-43428 Référence CVE CVE-2026-43429 https://www.cve.org/CVERecord?id=CVE-2026-43429 Référence CVE CVE-2026-43430 https://www.cve.org/CVERecord?id=CVE-2026-43430 Référence CVE CVE-2026-43432 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-017123LinuxのLinux KernelにおけるTime-of-check Time-of-use (TOCTOU) 競合状態の脆弱性

Linuxカーネルにおいて、以下の脆弱性が修正されました。cephの非同期unlink中に発生するi_nlinkアンダーランの問題の修正です。非同期unlinkの間、完了(最終的にi_nlinkを更新する処理)が来る前にi_nlinkカウンターを減少させてしまいます。これは「unlinkが成功すると仮定している」ために起きていました。この方法は悪い考えではありませんが、他のクライアントによる削除(または自身のunlinkの完了)と競合し、以下のようなWARNINGを引き起こすアンダーランとなります。具体的には、WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68 という警告が表示されます。ceph_unlink()内ではceph_mdsc_submit_request()がCEPH_MDS_OP_UNLINKのリクエストをMDSに送信しますが、完了を待ちません。この呼び出しと後続のdrop_nlink()呼び出しの間に、ワーカースレッドがCEPH_CAP_OP_IMPORT、CEPH_CAP_OP_GRANT、またはCEPH_MSG_CLIENT_REPLY(自身の完了の可能性あり)を処理する可能性があります。その結果、set_nlink()が呼ばれ、MDSから受け取った値でi_nlinkカウンターが更新されます。もし新しいi_nlinkの値が0の場合、それ以上の減少は違法ですが、ceph_unlink()は減少処理を行ってしまいます。WARNINGは次の手順で再現可能です。1. 非同期unlinkを強制します。非同期経路のみが影響を受けます。Ceph内部の詳細は不明ですが、MDSが「Fxr」権限を与えない理由はわかっていません。そこでget_caps_for_async_unlink()を常に成功するようにパッチしました。(このWARNINGは未パッチのカーネルでも発見されており、理論上のバグではありません。)2. ceph_mdsc_submit_request()の後にsleepを挿入し、unlink完了処理がdrop_nlink()の前にワーカースレッドで処理されるようにします。これによりdrop_nlink()実行前にi_nlinkが既に0となります。解決策としては、カウンターがすでに0の場合は減算をスキップすることですが、ロックなしでは依然として競合状態(TOCTOU問題)が発生します。ceph_fill_inode()とhandle_cap_grant()は共にset_nlink()実行中にceph_inode_info.i_ceph_lockスピンロックを保持しているため、このロックでi_nlinkの更新処理を保護することが適切だと考えられます。類似の先行例としてはNFSやSMB(inode.i_lock使用)、AFS(afs_vnode.cb_lock使用)があり、これらはいずれもゼロチェックを行っています。

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
Linux: 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < 9b31e88ac5623d15c8bc46f69dfe1d3b43a8f67c, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < 6d5fd8bb574bef039eb3b738e523870433a2aeb9, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < fcc477a6e8856c8a42b3c9e171724d8d6dfadd06, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < b3f5513141ecc6b277a8f7b7efe58a0cf9a5e859, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < aedd29386b23f3e1e6818943e11abfff2953732f, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < 7db008e85a5d17b64bc5390b828bf457ae91a415, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < 8975b85b0d45ca811ace6fac5907652f2310e5ac, 2ccb45462aeaf0831397b90d31d3d50a7704fa1f < ce0123cbb4a40a2f1bbb815f292b26e96088639f, 5.7
Fixed
Linux: < 5.7, 5.10.253 ≤ 5.10.*, 5.15.203 ≤ 5.15.*, 6.1.167 ≤ 6.1.*, 6.6.130 ≤ 6.6.*, 6.12.78 ≤ 6.12.*, 6.18.19 ≤ 6.18.*, 6.19.9 ≤ 6.19.*, 7.0 ≤ *
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 8 May 2026 · Last source change 11 May 2026, 22:24 UTC · CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-28726
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
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-2026-43420 · cve.blacktree.nl