CVE-2025-21945 ksmbd: fix use-after-free in smb2_lock
A use-after-free vulnerability in the Linux kernel's ksmbd module allows attackers to potentially execute arbitrary code or escalate privileges.
- 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-2025-21945?
CVE-2025-21945 is a high-severity use after free vulnerability in Linux kernel, published on 1 Apr 2025. 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: fix use-after-free in smb2_lock
If smb_lock->zero_len has value, ->llist of smb_lock is not delete and flock is old one. It will cause use-after-free on error handling routine.
Weakness: CWE-416
Which versions are affected by CVE-2025-21945?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21945?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-21945 being exploited?
There is no known exploitation of CVE-2025-21945 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21945, DEBIAN-CVE-2025-21945, GHSA-5g8p-x9mm-c9vr, ROOT-OS-UBUNTU-2204-CVE-2025-21945, ROOT-OS-UBUNTU-2404-CVE-2025-21945, UBUNTU-CVE-2025-21945.