# CVE-2026-99131: xfs: fix capability check in xfs


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** AZL-111245, BELL-CVE-2026-99131, DEBIAN-CVE-2026-99131, GHSA-5g3h-v4h7-rrh3, UBUNTU-CVE-2026-99131

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99131 and fix it if it is affected.

What it is: CVE-2026-99131 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99131 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-99131/ (Markdown: https://insights.sbomify.com/CVE-2026-99131/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99131
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99131
- OSV: https://osv.dev/vulnerability/CVE-2026-99131

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99131/
Summaries are generated and may contain mistakes; the official description above is the record.