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CVE Record

CVE-2025-40203: listmount: don't call path_put() under namespace semaphore

In the Linux kernel, the following vulnerability has been resolved: listmount: don't call path_put() under namespace semaphore Massage listmount() and make sure we don't call path_put() under the namespace semaphore. If we put the last reference we're fscked.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A low-privileged local user may trigger unsafe Linux kernel mount-listing cleanup, potentially compromising confidentiality, integrity, and availability. Network-only attackers are not indicated by the supplied CVSS vector. Systems should receive corrected vendor kernels promptly, especially shared or multi-user hosts.

Executive priority

Treat as a high-priority local privilege-boundary risk, not an unauthenticated internet emergency. Accelerate remediation on systems where untrusted users or workloads have local access; schedule other affected hosts through the normal urgent patch cycle.

Technical view

The flaw occurs when listmount() can call path_put() while holding the namespace semaphore. Dropping the final path reference in that state may cause severe kernel failure or corruption. The supplied CVSS 3.1 rating is 7.8: local access, low complexity, low privileges, no user interaction, and high impacts.

Likely exposure

The bundle marks Linux kernel versions 6.8, 6.12.54, 6.17.4, and 6.18 as affected. Its version data does not clearly define complete ranges or distribution backports, so exposure must be confirmed against each vendor kernel build and changelog.

Exploitation context

The supplied record does not list this CVE in CISA KEV and provides no evidence of active exploitation or public exploit availability. The CVSS vector indicates exploitation requires local, low-privileged access and no user interaction.

Researcher notes

The source bundle supplies no CWE and does not precisely map each fix commit to affected stable branches. Avoid inferring a specific vulnerability class beyond unsafe reference release under namespace locking. Confirm ancestry or vendor backports before declaring a build vulnerable or fixed.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable referenced stable fix.
  • Check distribution security guidance for backported fixes and corrected package versions.
  • Prioritize shared, multi-user, container-hosting, and other systems granting untrusted local access.
  • Reboot into the corrected kernel after installation, following operational change controls.

Validation and detection

  • Inventory running kernel versions and distribution package revisions across Linux systems.
  • Compare each build with vendor advisories, changelogs, and the referenced stable commits.
  • Confirm the corrected kernel is active after reboot, not merely installed.
  • Re-scan assets and document exceptions where vendor remediation remains unavailable.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2025-40203 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-40203Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxb4c2bea8ceaa50cd42a8f73667389d801a3ecf2d, b4c2bea8ceaa50cd42a8f73667389d801a3ecf2d, b4c2bea8ceaa50cd42a8f73667389d801a3ecf2dunaffected
LinuxLinux6.8, 0, 6.12.54, 6.17.4, 6.18affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.