# CVE-2026-90318: fat: release buffer head after rebuilding parent

> A missing buffer head release in the Linux kernel FAT filesystem can lead to memory corruption and denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102612, BELL-CVE-2026-90318, DEBIAN-CVE-2026-90318, GHSA-qqhm-c5f5-75r9, UBUNTU-CVE-2026-90318

## What is CVE-2026-90318?

CVE-2026-90318 is a memory corruption vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

fat: release buffer head after rebuilding parent

fat_scan_logstart() leaves the matching directory entry's buffer head in
sinfo.bh for the caller to release, just like fat_scan().

fat_rebuild_parent() uses the directory entry to rebuild the parent inode
for the nostale_ro NFS export path, but does not release sinfo.bh after a
successful scan.  Release it once fat_build_inode() has consumed the
directory entry data.

## Which versions are affected by CVE-2026-90318?


## How do I fix CVE-2026-90318?

Apply the vendor's patch.

## Is CVE-2026-90318 being exploited?

There is no known exploitation of CVE-2026-90318 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90318 and fix it if it is affected.

What it is: CVE-2026-90318 is a memory corruption vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90318 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-2026-90318/ (Markdown: https://insights.sbomify.com/CVE-2026-90318/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90318
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90318
- OSV: https://osv.dev/vulnerability/CVE-2026-90318

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90318/
Summaries are generated and may contain mistakes; the official description above is the record.