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CVE Record

CVE-2025-21769: ptp: vmclock: Add .owner to vmclock_miscdev_fops

In the Linux kernel, the following vulnerability has been resolved: ptp: vmclock: Add .owner to vmclock_miscdev_fops Without the .owner field, the module can be unloaded while /dev/vmclock0 is open, leading to an oops.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw can crash an affected system when the vmclock device remains open while its module is unloaded. It is not described as data theft or remote compromise; the main business risk is local denial of service on systems exposing this device.

Executive priority

Treat this as a moderate availability issue. It matters most for shared, virtualized, or production Linux systems where a local user-triggered crash could disrupt service. It is not supported by the sources as remotely exploitable or actively exploited.

Technical view

The vmclock misc device file operations lacked an .owner field. Without module ownership protection, the module could be unloaded while /dev/vmclock0 was open, causing a kernel oops. CVSS 3.1 is 5.5: local, low complexity, low privilege, no user interaction, availability impact only.

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions, including the listed 6.13, 6.13.4, and 6.14 entries, where vmclock is present and local users can access /dev/vmclock0.

Exploitation context

The source bundle does not indicate active exploitation, and KEV status is false. The scenario is local rather than remote and requires low privileges. The documented impact is a kernel oops, which should be treated as a denial-of-service risk.

Researcher notes

Focus on vmclock_miscdev_fops module lifetime handling. The fix adds .owner to prevent unload while the device is open. No CWE, exploit evidence, or distribution-specific package status is provided in the source bundle, so confirm downstream backports before declaring systems fixed.

Mitigation direction

  • Check vendor or distribution kernel advisories for patched builds containing the referenced fix.
  • Prioritize kernel updates on multi-user hosts exposing /dev/vmclock0.
  • Restrict local access to vmclock devices where operationally possible.
  • Avoid manual kernel deployment shortcuts; follow vendor update guidance.

Validation and detection

  • Inventory Linux hosts and identify kernel versions matching the affected range.
  • Confirm whether /dev/vmclock0 exists on candidate systems.
  • Review package changelogs for the referenced stable kernel commits.
  • Verify local user access policies for vmclock device nodes.
Prepared
Confidence
medium
Sources
4

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-2025-21769 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
1ADP providers
3Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

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
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2025-21769Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux20503272422693d793b84f88bf23fe4e955d3a33, 20503272422693d793b84f88bf23fe4e955d3a33unaffected
LinuxLinux6.13, 0, 6.13.4, 6.14affected
Weakness

CWE details

No CWE listed

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