VulnerabilityPublished 28 Oct 2026

CVE-2026-99131: Linux kernel · xfs: fix capability check in xfs

Source GCVE Database

Authoritative record:CVE-2026-99131

Not known to be exploited · fixed in e2f62a9744ebad3bcb6347a648e615026e9efeff : update Linux kernel when convenient.

Data as of 28 Oct 2026, 14:13 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in e2f62a9744ebad3bcb6347a648e615026e9efeff, 7809ac0161c7c5f52ed348fb1ec683b2b454a83e, 19a1a22029ad3ae3604c763af6bd1195cb73648f

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-5g3h-v4h7-rrh3

What to do

Upgrade Linux kernel to e2f62a9744ebad3bcb6347a648e615026e9efeff, 7809ac0161c7c5f52ed348fb1ec683b2b454a83e or 19a1a22029ad3ae3604c763af6bd1195cb73648f.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ eba0549bc7d100691c13384b774346b8aa9cf9a9, < e2f62a9744ebad3bcb6347a648e615026e9efeff	Fixed in e2f62a9744ebad3bcb6347a648e615026e9efeff
LinuxLinux	Affected ≥ eba0549bc7d100691c13384b774346b8aa9cf9a9, < 7809ac0161c7c5f52ed348fb1ec683b2b454a83e	Fixed in 7809ac0161c7c5f52ed348fb1ec683b2b454a83e
LinuxLinux	Affected ≥ eba0549bc7d100691c13384b774346b8aa9cf9a9, < 19a1a22029ad3ae3604c763af6bd1195cb73648f	Fixed in 19a1a22029ad3ae3604c763af6bd1195cb73648f
LinuxLinux	Affected =5.18	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel by correcting the capability check function used in the XFS quota code. Users should apply the updated kernel version containing this fix. No additional mitigation steps are indicated or required beyond applying the official patch.

Description

A vulnerability in the Linux kernel's XFS filesystem capability check allowed users to bypass group quota enforcement by changing a file's group ID to another group the user belonged to. This was due to a semantic difference between two capability checking functions, leading to quota accounting being bypassed in some cases such as via NFS clients. The issue has been fixed by using the correct capability check function to prevent quota bypass and unnecessary SELinux audit messages.

Impact

The vulnerability allowed users to bypass group quota enforcement on XFS filesystems by changing file group IDs under certain conditions, potentially leading to quota limits being exceeded without enforcement. This could affect resource management and quota policies on systems using XFS, especially in networked environments using NFS. There is no indication of remote code execution or privilege escalation beyond quota bypass. No known exploits in the wild have been reported.

References

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