CVE-2025-68226 smb: client: fix incomplete backport in cfids_invalidation_worker()
A use-after-free vulnerability in the Linux kernel SMB client allows attackers to potentially execute code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-68226?
CVE-2025-68226 is a high-severity use after free vulnerability in Linux, published on 16 Dec 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix incomplete backport in cfids_invalidation_worker()
The previous commit bdb596ceb4b7 ("smb: client: fix potential UAF in smb2_close_cached_fid()") was an incomplete backport and missed one kref_put() call in cfids_invalidation_worker() that should have been converted to close_cached_dir().
Which versions are affected by CVE-2025-68226?
How do I fix CVE-2025-68226?
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-2025-68226 being exploited?
There is no known exploitation of CVE-2025-68226 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2025-68226, GHSA-gqrv-x663-5498, UBUNTU-CVE-2025-68226.