CVE-2026-90167 ksmbd: serialize oplock close with pending break ownership
A race condition in the Linux kernel ksmbd module allows attackers to cause denial of service or potentially execute code via oplock break handling.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90167?
CVE-2026-90167 is a vulnerability in Linux, published on 17 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: serialize oplock close with pending break ownership
close may abort an in-flight oplock break while another breaker already holds an opinfo reference. Releasing pending_break wakes that waiter, but without serializing the close transition with bit acquisition it can become a new break owner through the test_and_set_bit() fast path. It can then overwrite OPLOCK_CLOSING with OPLOCK_ACK_WAIT and continue a break for a dying opinfo.
Make OPLOCK_CLOSING terminal once the opinfo is removed from the inode list. Serialize that transition, pending_break acquisition, and OPLOCK_ACK_WAIT setup with an opinfo state lock. A breaker which loses the race releases its ownership and returns -ENOENT. Explicitly wake pending_break waiters during close so they can observe the terminal state.
Also prevent ACK and timeout paths from replacing OPLOCK_CLOSING with OPLOCK_STATE_NONE.
Which versions are affected by CVE-2026-90167?
How do I fix CVE-2026-90167?
Apply the vendor's patch.
Is CVE-2026-90167 being exploited?
There is no known exploitation of CVE-2026-90167 in the wild and no public exploit code.
Sources
Also known as AZL-102911, BELL-CVE-2026-90167, DEBIAN-CVE-2026-90167, GHSA-923f-jcq6-gqvq, UBUNTU-CVE-2026-90167.