# CVE-2025-68299: afs: Fix delayed allocation of a cell's anonymous key

> A null pointer dereference in the Linux kernel AFS filesystem can cause a system crash when mounting a cell before the anonymous key is allocated.

- **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:** 16 Dec 2025
- **Updated:** 3 Aug 2026
- **Also known as:** DEBIAN-CVE-2025-68299, GHSA-wq3w-wxhr-h474, UBUNTU-CVE-2025-68299

## What is CVE-2025-68299?

CVE-2025-68299 is a vulnerability in Linux, published on 16 Dec 2025. 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:

afs: Fix delayed allocation of a cell's anonymous key

The allocation of a cell's anonymous key is done in a background thread
along with other cell setup such as doing a DNS upcall.  In the reported
bug, this is triggered by afs_parse_source() parsing the device name given
to mount() and calling afs_lookup_cell() with the name of the cell.

The normal key lookup then tries to use the key description on the
anonymous authentication key as the reference for request_key() - but it
may not yet be set and so an oops can happen.

This has been made more likely to happen by the fix for dynamic lookup
failure.

Fix this by firstly allocating a reference name and attaching it to the
afs_cell record when the record is created.  It can share the memory
allocation with the cell name (unfortunately it can't just overlap the cell
name by prepending it with "afs@" as the cell name already has a '.'
prepended for other purposes).  This reference name is then passed to
request_key().

Secondly, the anon key is now allocated on demand at the point a key is
requested in afs_request_key() if it is not already allocated.  A mutex is
used to prevent multiple allocation for a cell.

Thirdly, make afs_request_key_rcu() return NULL if the anonymous key isn't
yet allocated (if we need it) and then the caller can return -ECHILD to
drop out of RCU-mode and afs_request_key() can be called.

Note that the anonymous key is kind of necessary to make the key lookup
cache work as that doesn't currently cache a negative lookup, but it's
probably worth some investigation to see if NULL can be used instead.

## Which versions are affected by CVE-2025-68299?


## How do I fix CVE-2025-68299?

Apply the vendor's patch.

## Is CVE-2025-68299 being exploited?

There is no known exploitation of CVE-2025-68299 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68299 and fix it if it is affected.

What it is: CVE-2025-68299 is a vulnerability in Linux, published on 16 Dec 2025. 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-2025-68299 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-2025-68299/ (Markdown: https://insights.sbomify.com/CVE-2025-68299/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68299
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68299
- OSV: https://osv.dev/vulnerability/CVE-2025-68299

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68299/
Summaries are generated and may contain mistakes; the official description above is the record.