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Full vulnerability report · 2026
CVE-2026-76642High confidence

util-linux libmount Privilege Escalation via Failed Mount Helper

util-linux · util-linux

Official source article: GitHub GHSA-M25X-3HJ9-M26F ↗. Check the applicable product and release in the original source.

8.5HighCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 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:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.22% 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.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs util-linux util-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: Within 30 daysRemediation target: Within 180 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 2 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

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

7 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 2 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
Alpine v3.23v3.23 · mainutil-linuxVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.41.6-r0Alpine Security Database ↗Source updated 3 Oct 2026
Alpine v3.22v3.22 · mainutil-linuxVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.2.41.6-r0Alpine Security Database ↗Source updated 3 Oct 2026
Debian trixietrixie · sourceutil-linuxAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourceutil-linuxAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourceutil-linuxVendor fix publishedDebian records a fixed source-package version for this release.2.42.3-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourceutil-linuxVendor fix publishedDebian records a fixed source-package version for this release.2.42.3-1Debian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveutil-linuxUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.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.

2 current
CVE-2026-76642 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityutil-linux: util-linux: failed external mount helper still runs privileged X-mount post-hooks
15 known affected

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

  • libblkid as a component of Red Hat Enterprise Linux 10
  • libblkid-devel as a component of Red Hat Enterprise Linux 10
  • libfdisk as a component of Red Hat Enterprise Linux 10
  • libfdisk-devel as a component of Red Hat Enterprise Linux 10
  • libmount as a component of Red Hat Enterprise Linux 10
  • libmount-devel as a component of Red Hat Enterprise Linux 10
  • libsmartcols as a component of Red Hat Enterprise Linux 10
  • libsmartcols-devel as a component of Red Hat Enterprise Linux 10
  • libuuid as a component of Red Hat Enterprise Linux 10
  • libuuid-devel as a component of Red Hat Enterprise Linux 10
  • python3-libmount as a component of Red Hat Enterprise Linux 10
  • util-linux as a component of Red Hat Enterprise Linux 10
Summary
When an external mount. helper runs but exits with a nonzero status, libmount still treats the helper invocation as successful and runs privileged post-mount hooks. A local unprivileged user with an /etc/fstab entry that uses the user option together with X-mount.idmap or X-mount.owner/group/mode can cause those hooks to clone or re-own the underlying filesystem after the helper fails, leading to local privilege escalation.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
CVE-2026-76642 · CSAF 2.0 · revision 7 · interimSUSE Product Security TeamCVE-2026-76642
642 known affected

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

  • libblkid-devel as component of SUSE Linux Enterprise Desktop 15 SP7
  • libblkid-devel-static as component of SUSE Linux Enterprise Desktop 15 SP7
  • libblkid1 as component of SUSE Linux Enterprise Desktop 15 SP7
  • libblkid1-32bit as component of SUSE Linux Enterprise Desktop 15 SP7
  • libfdisk-devel as component of SUSE Linux Enterprise Desktop 15 SP7
  • libfdisk1 as component of SUSE Linux Enterprise Desktop 15 SP7
  • libmount-devel as component of SUSE Linux Enterprise Desktop 15 SP7
  • libmount1 as component of SUSE Linux Enterprise Desktop 15 SP7
  • libmount1-32bit as component of SUSE Linux Enterprise Desktop 15 SP7
  • libsmartcols-devel as component of SUSE Linux Enterprise Desktop 15 SP7
  • libsmartcols1 as component of SUSE Linux Enterprise Desktop 15 SP7
  • libuuid-devel as component of SUSE Linux Enterprise Desktop 15 SP7
Summary
util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
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-2026-70382

No EUVD known-exploited evidence

util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.

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
8.5 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 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

util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.

What

util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.

Why

The product detects a specific error, but takes no actions to handle the error.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

What

util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.

Why

The product detects a specific error, but takes no actions to handle the error.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

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.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
local access → Detection of Error Condition Without Action → gain additional privileges
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
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-390 ↗

CWE-390: Detection of Error Condition Without Action. The product detects a specific error, but takes no actions to handle the error.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: 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.ATNoneAttack requirements: No additional deployment or execution condition is required.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
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.
Privilege escalationCWE-390Public exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-70382Official EUVD mapping

util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3180util-linux: Schwachstelle ermöglicht Privilegieneskalation

Ein lokaler Angreifer kann eine Schwachstelle in util-linux ausnutzen, um seine Privilegien zu erhöhen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260909Security Bulletin 9 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 9 Sep 2026, published on 9 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

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
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 3 Sept 2026 · Last source change 3 Sept 2026, 14:00 UTC · CWE-390 · Detection of Error Condition Without Action

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 2026-09-03
European sourceENISA EUVD · EUVD-2026-70382
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    libblkid as a component of Red Hat Enterprise Linux 10; libblkid-devel as a component of Red Hat Enterprise Linux 10; libfdisk as a component of Red Hat Enterprise Linux 10; libfdisk-devel as a component of Red Hat Enterprise Linux 10; libmount as a component of Red Hat Enterprise Linux 10; libmount-devel as a component of Red Hat Enterprise Linux 10; libsmartcols as a component of Red Hat Enterprise Linux 10; libsmartcols-devel as a component of Red Hat Enterprise Linux 10; libuuid as a component of Red Hat Enterprise Linux 10; libuuid-devel as a component of Red Hat Enterprise Linux 10; python3-libmount as a component of Red Hat Enterprise Linux 10; util-linux as a component of Red Hat Enterprise Linux 10; util-linux-core as a component of Red Hat Enterprise Linux 10; util-linux.src as a component of Red Hat Enterprise Linux 10; uuidd as a component of Red Hat Enterprise Linux 10 · Fixed: util-linux-main@aarch64 as a component of Red Hat Hardened Images; util-linux-main@src as a component of Red Hat Hardened Images; util-linux-main@x86_64 as a component of Red Hat Hardened Images
    After
    libblkid as a component of Red Hat Enterprise Linux 10; libblkid-devel as a component of Red Hat Enterprise Linux 10; libfdisk as a component of Red Hat Enterprise Linux 10; libfdisk-devel as a component of Red Hat Enterprise Linux 10; libmount as a component of Red Hat Enterprise Linux 10; libmount-devel as a component of Red Hat Enterprise Linux 10; libsmartcols as a component of Red Hat Enterprise Linux 10; libsmartcols-devel as a component of Red Hat Enterprise Linux 10; libuuid as a component of Red Hat Enterprise Linux 10; libuuid-devel as a component of Red Hat Enterprise Linux 10; python3-libmount as a component of Red Hat Enterprise Linux 10; util-linux as a component of Red Hat Enterprise Linux 10; util-linux-core as a component of Red Hat Enterprise Linux 10; util-linux.src as a component of Red Hat Enterprise Linux 10; uuidd as a component of Red Hat Enterprise Linux 10 · Fixed: libblkid-0:2.42.2-3.4.hum1@aarch64 as a component of Red Hat Hardened Images; libblkid-0:2.42.2-3.4.hum1@x86_64 as a component of Red Hat Hardened Images; util-linux-0:2.42.2-3.4.hum1@src as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
  2. ENISA EUVD mappingEUVD-2026-70382 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-70382"}
    ENISA EUVD ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    util-linux: 2.39 < 2.41.6, 2.42 < 2.42.3 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    After
    util-linux: 2.39 < 2.41.6, 2.42 < 2.42.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  4. Vendor guidanceAuthoritative vendor guidance changed: removed remediation: access.redhat.com/CVE-2026-76642.
    Before
    remediation: access.redhat.com/CVE-2026-76642
    After
    no authoritative guidance recorded
    CNA ↗
  5. Affected versionsThe structured affected or fixed version information changed.
    Before
    2.39 < 2.41.6; 2.42 < 2.42.3 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    After
    util-linux: 2.39 < 2.41.6, 2.42 < 2.42.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  6. Remediation statusRemediation status changed from Patch available to Awaiting fix.
    Before
    Patch available
    After
    Awaiting fix
    CNA ↗
  7. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  8. Affected versionsThe structured affected or fixed version information changed.
    Before
    util-linux: 2.39 < 2.41.6, 2.42 < 2.42.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    util-linux: 2.39 < 2.41.6, 2.42 < 2.42.3 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    Red Hat Product Security ↗
  9. Affected versionsThe structured affected or fixed version information changed.
    Before
    2.39 < 2.41.6; 2.42 < 2.42.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    2.39 < 2.41.6; 2.42 < 2.42.3 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    Red Hat Product Security ↗
  10. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  11. Vendor guidanceAuthoritative vendor guidance changed: removed patch: github.com/1d14676ea70003e9f5b2a6a76af0cadb1190411a; removed patch: github.com/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc; 3 further removals.
    Before
    patch: github.com/1d14676ea70003e9f5b2a6a76af0cadb1190411a · patch: github.com/a15c00a9e545aa8b9cf6ec0f888ff6c7b3eaeedc · patch: github.com/f57cea130839c0af8dc0525274267ae4cfd66bbf · 2 more references
    After
    no authoritative guidance recorded
    CNA ↗
  12. Affected versionsThe structured affected or fixed version information changed.
    Before
    2.39 < 2.41.6; 2.42 < 2.42.3 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    2.39 < 2.41.6; 2.42 < 2.42.3 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  13. Remediation statusRemediation status changed from Patch available to Awaiting fix.
    Before
    Patch available
    After
    Awaiting fix
    CNA ↗
  14. 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 recorded from official guidance
Fixed release recorded from official guidance
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-70382↗Red Hat Product Security security advisory↗CISA Vulnrichment SSVC evidence↗CVE authority or vendor reference · GitHub GHSA-M25X-3HJ9-M26F↗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-2026-76642 · cve.blacktree.nl