CVE-2026-89831 f2fs: protect critical_task_priority updates with s_umount
A race condition in the Linux kernel f2fs filesystem allows local attackers to cause a denial of service by racing sysfs writes with thread teardown.
- 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-2026-89831?
CVE-2026-89831 is a vulnerability in Linux, published on 16 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:
f2fs: protect critical_task_priority updates with s_umount
The sysfs store path already takes s_umount for GC thread control entries, and ckpt_thread_ioprio is covered as well.
critical_task_priority also updates checkpoint or GC kthread scheduling state, but it is not covered by that serialization. It can race with remount or teardown paths that are stopping those threads.
Protect critical_task_priority sysfs writes with s_umount too.
Which versions are affected by CVE-2026-89831?
How do I fix CVE-2026-89831?
Apply the vendor's patch.
Is CVE-2026-89831 being exploited?
There is no known exploitation of CVE-2026-89831 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-89831, GHSA-gh89-f7g4-6qgp, UBUNTU-CVE-2026-89831.