# CVE-2026-68357: watchdog: pretimeout: Fix UAF in watchdog_unregister_governor()

> A use-after-free in the Linux kernel watchdog subsystem allows local attackers with high privileges to execute arbitrary code or escalate privileges.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-68357, DEBIAN-CVE-2026-68357, GHSA-fjcx-ggvr-3wg6, UBUNTU-CVE-2026-68357

## What is CVE-2026-68357?

CVE-2026-68357 is an use after free vulnerability in Linux, published on 10 Aug 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:

watchdog: pretimeout: Fix UAF in watchdog_unregister_governor()

When a watchdog governor is unregistered, it updates existing watchdog
devices that were using this governor by falling back to `default_gov`.

If the governor being unregistered is currently set as `default_gov`,
the `default_gov` is never cleared.  This leads to 2 use-after-free
issues:
1. New watchdog devices registered after this point will inherit the
   dangling `default_gov`.
2. Existing watchdog devices using the unregistered governor will have
   their `wdd->gov` reassigned to the dangling `default_gov`.

Fix the UAF by clearing `default_gov` if it matches the governor being
unregistered.

## Which versions are affected by CVE-2026-68357?


## How do I fix CVE-2026-68357?

Apply the vendor's patch.

## Is CVE-2026-68357 being exploited?

There is no known exploitation of CVE-2026-68357 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68357 and fix it if it is affected.

What it is: CVE-2026-68357 is an use after free vulnerability in Linux, published on 10 Aug 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-2026-68357 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-2026-68357/ (Markdown: https://insights.sbomify.com/CVE-2026-68357/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68357
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68357
- OSV: https://osv.dev/vulnerability/CVE-2026-68357

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68357/
Summaries are generated and may contain mistakes; the official description above is the record.