CVE-2026-99131 xfs: fix capability check in xfs
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99131?
CVE-2026-99131 is a vulnerability in Linux, published on 28 Oct 2026.
Official description
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:
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()
Which versions are affected by CVE-2026-99131?
How do I fix CVE-2026-99131?
Upgrade to a fixed version.
Is CVE-2026-99131 being exploited?
There is no known exploitation of CVE-2026-99131 in the wild and no public exploit code.
Sources
Also known as AZL-111245, BELL-CVE-2026-99131, DEBIAN-CVE-2026-99131, GHSA-5g3h-v4h7-rrh3, UBUNTU-CVE-2026-99131.