CVE-2026-93261 locking/lockdep: Fix NULL pointer dereference in __lock_set_class()
A NULL pointer dereference in the Linux kernel lockdep subsystem can cause a system crash when the lock class pool is exhausted.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93261?
CVE-2026-93261 is a vulnerability in Linux, published on 24 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:
locking/lockdep: Fix NULL pointer dereference in __lock_set_class()
register_lock_class() can return NULL when the lock class pool is exhausted, graph_lock() fails, or key validation fails. However, __lock_set_class() uses the return value directly in pointer arithmetic without a NULL check:
class = register_lock_class(lock, subclass, 0); hlock->class_idx = class - lock_classes;
If class is NULL, this computes a wild offset that corrupts hlock->class_idx. The subsequent reacquire_held_locks() call will invoke hlock_class() with this corrupted index, leading to a NULL or out-of-bounds pointer dereference.
Add the missing NULL check, consistent with how __lock_acquire() already handles this case at the same call site.
Which versions are affected by CVE-2026-93261?
How do I fix CVE-2026-93261?
Apply the vendor's patch.
Is CVE-2026-93261 being exploited?
There is no known exploitation of CVE-2026-93261 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-93261, DEBIAN-CVE-2026-93261, GHSA-mh76-8wxp-345h, UBUNTU-CVE-2026-93261.