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Response snapshot Oct 31, 2026, 14:16 UTC

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VulnerabilityCVE-2026-99131

Linux kernel: xfs: fix capability check in xfs

In the Linux kernel, the following vulnerability has been resolved: xfs: fix capability check in xfs An user reported a bug where he managed to evade group's quota by changing a file's gid to a different group id the same user belonged to, even though quotas were enforced on both gids and the file's size was big enough to exceed the quota's hardlimit.

At a glance

Exploited
Not known
Severity
8.2 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-99131 (opens a new tab)

What happened

In the Linux kernel, the following vulnerability has been resolved:

xfs: fix capability check in xfs

An user reported a bug where he managed to evade group's quota by changing a file's gid to a different group id the same user belonged to, even though quotas were enforced on both gids and the file's size was big enough to exceed the quota's hardlimit.

Commit eba0549bc7d1 replaced a capable() call by a has_capability_noaudit() to prevent unnecessary selinux audit messages. Turns out that both calls have slightly different semantics even though their documentation seems similar. Where in a nutshell:

Continue reading

capable() - Tests the task's effective credentials has_ns_capability_noaudit() - Tests the task's real credentials

This most of the time has no practical difference but in some cases like changing attrs (specifically group id in this case) through a NFS client this will allow the quota code to use XFS_QMOPT_FORCE_RES, effectively bypassing quota accounting checks.

Using instead ns_capable_noaudit() should fix this issue and prevent selinux audit messages.

This also fix the remaining calls to has_capability_noaudit()

Scores and how they were measured

CVSS base severity

8.2

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-99131 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 31). Linux kernel: xfs: fix capability check in xfs (CVE-2026-99131). https://kevwire.com/record/CVE-2026-99131

MLA

"Linux kernel: xfs: fix capability check in xfs (CVE-2026-99131)." KEVWire, 31 Oct. 2026, kevwire.com/record/CVE-2026-99131.

Chicago

KEVWire. "Linux kernel: xfs: fix capability check in xfs (CVE-2026-99131)." Last modified October 31, 2026. https://kevwire.com/record/CVE-2026-99131.

Evidence summary (plain text)

Linux kernel: xfs: fix capability check in xfs (Oct 28, 2026).
In the Linux kernel, the following vulnerability has been resolved:

xfs: fix capability check in xfs

An user reported a bug where he managed to evade group's quota
by changing a file's gid to a different group id the same user
belonged to, even though quotas were enforced on both gids and the
file's size was big enough to exceed the quota's hardlimit.

Commit eba0549bc7d1 replaced a capable() call by a
has_capability_noaudit() to prevent unnecessary selinux audit messages.
Turns out that both calls have slightly different semantics even though
their documentation seems similar.
CVSS 8.2 (version 3.1; evidence as of Oct 31, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-99131).
Sources:
NVD CVE-2026-99131: https://nvd.nist.gov/vuln/detail/CVE-2026-99131
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-31T12:40:58.114Z&lastModEndDate=2026-10-31T14:15:57.636Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-31T10:50:56.512Z&lastModEndDate=2026-10-31T13:40:56.165Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-99131.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 31, 2026, 14:15 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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