CVE-2025-40146 blk-mq: fix potential deadlock while nr_requests grown
A local attacker with high privileges can trigger a deadlock in the Linux kernel block layer, causing a denial of service.
- 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-2025-40146?
CVE-2025-40146 is a denial of service vulnerability in Linux, published on 12 Nov 2025. 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:
blk-mq: fix potential deadlock while nr_requests grown
Allocate and free sched_tags while queue is freezed can deadlock[1], this is a long term problem, hence allocate memory before freezing queue and free memory after queue is unfreezed.
[1] https://lore.kernel.org/all/[email protected]/
Which versions are affected by CVE-2025-40146?
How do I fix CVE-2025-40146?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-40146 being exploited?
There is no known exploitation of CVE-2025-40146 in the wild and no public exploit code.
Sources
Also known as AZL-70004, BELL-CVE-2025-40146, DEBIAN-CVE-2025-40146, GHSA-mh62-fv56-v5jj, ROOT-OS-DEBIAN-11-CVE-2025-40146, ROOT-OS-DEBIAN-12-CVE-2025-40146 and 4 more.