CVE-2025-21944 ksmbd: fix bug on trap in smb2_lock
A bug in the ksmbd SMB2 lock handling can cause a kernel trap, leading to a denial of service.
- 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-2025-21944?
CVE-2025-21944 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Apr 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:
ksmbd: fix bug on trap in smb2_lock
If lock count is greater than 1, flags could be old value. It should be checked with flags of smb_lock, not flags. It will cause bug-on trap from locks_free_lock in error handling routine.
Weakness: CWE-667
Which versions are affected by CVE-2025-21944?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21944?
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-2025-21944 being exploited?
There is no known exploitation of CVE-2025-21944 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21944, DEBIAN-CVE-2025-21944, GHSA-q86w-66m5-qpj3, ROOT-OS-UBUNTU-2204-CVE-2025-21944, ROOT-OS-UBUNTU-2404-CVE-2025-21944, UBUNTU-CVE-2025-21944.