CVE-2026-74395 RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference
A local attacker with low privileges can trigger a NULL pointer dereference in the Linux kernel RDMA subsystem, causing a system crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74395?
CVE-2026-74395 is a vulnerability in Linux, published on 15 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:
RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference
MLX5_IB_METHOD_DEVX_SUBSCRIBE_EVENT() links event_sub into sub_list before initializing the fields used by the shared error path.
If eventfd_ctx_fdget() then fails, the unwind path dereferences event_sub->ev_file in uverbs_uobject_put() and calls subscribe_event_xa_dealloc() with an unset xa_key_level1.
subscribe_event_xa_alloc() creates the XA entry exactly once for a given key_level1, on the first occurrence of that key. The unwind path must therefore call subscribe_event_xa_dealloc() exactly once for it as well.
Enforce that by adding devx_key_in_sub_list() and calling subscribe_event_xa_dealloc() only when the last matching pending entry is being cleaned up.
Which versions are affected by CVE-2026-74395?
How do I fix CVE-2026-74395?
Apply the vendor's patch.
Is CVE-2026-74395 being exploited?
There is no known exploitation of CVE-2026-74395 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74395, DEBIAN-CVE-2026-74395, GHSA-x75h-3pjw-vh4q, UBUNTU-CVE-2026-74395.