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.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
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.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-68357 being exploited?
There is no known exploitation of CVE-2026-68357 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68357, DEBIAN-CVE-2026-68357, GHSA-fjcx-ggvr-3wg6, UBUNTU-CVE-2026-68357.