# CVE-2026-80809: ocfs2: fix missing metadata reservation for large xattrs

> A local attacker can crash the Linux kernel by setting a large extended attribute on a fragmented OCFS2 filesystem due to missing metadata reservation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99462, BELL-CVE-2026-80809, DEBIAN-CVE-2026-80809, GHSA-4q7v-w8cm-5gq2, UBUNTU-CVE-2026-80809

## What is CVE-2026-80809?

CVE-2026-80809 is a denial of service vulnerability in Linux, published on 4 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:

ocfs2: fix missing metadata reservation for large xattrs

[BUG]
lsetxattr() panics the kernel when setting a large xattr value on a
fragmented filesystem where the file already has an external xattr
block.

[CAUSE]
ocfs2_calc_xattr_set_need() never reserves metadata blocks for a new
xattr value's extent tree when the file already has an external xattr
block. The not_found path leaves meta_add at zero, so meta_ac is NULL
when ocfs2_xattr_extend_allocation() runs.

A new value root has room for a single extent record. On a fragmented
filesystem, the allocator cannot satisfy the xattr value in one
contiguous run, so each non-contiguous run requires its own extent
record. When the value root's extent list is full and meta_ac is NULL,
ocfs2_add_clusters_in_btree() returns RESTART_META, and
ocfs2_xattr_extend_allocation() hits BUG_ON(why == RESTART_META).

[FIX]
The case where no xattr block exists yet already calls
ocfs2_extend_meta_needed(&def_xv.xv.xr_list) to reserve value tree
metadata. Add the same reservation to the case where an xattr block
already exists, making the two cases consistent.

Replace the BUG_ON with a -ENOSPC return so that if RESTART_META is
returned despite the reservation, the error propagates to userspace
instead of panicking the kernel.

## Which versions are affected by CVE-2026-80809?


## How do I fix CVE-2026-80809?

Apply the vendor's patch.

## Is CVE-2026-80809 being exploited?

There is no known exploitation of CVE-2026-80809 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80809 and fix it if it is affected.

What it is: CVE-2026-80809 is a denial of service vulnerability in Linux, published on 4 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-2026-80809 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-2026-80809/ (Markdown: https://insights.sbomify.com/CVE-2026-80809/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80809
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80809
- OSV: https://osv.dev/vulnerability/CVE-2026-80809

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80809/
Summaries are generated and may contain mistakes; the official description above is the record.