CVE-2026-74349 ocfs2: reject FITRIM ranges shorter than a cluster
An integer underflow in the OCFS2 filesystem allows a local attacker to cause a denial of service by triggering a FITRIM operation with a specific range size.
- 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-2026-74349?
CVE-2026-74349 is a high-severity 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:
ocfs2: reject FITRIM ranges shorter than a cluster
ocfs2_trim_mainbm() trims the global bitmap in cluster units, but its too-short range validation only checks sb->s_blocksize.
On filesystems with a cluster size larger than the block size, a FITRIM range that is at least one block but shorter than one cluster is accepted and shifted down to len == 0. The later start + len - 1 and len -= ... arithmetic then underflows and can drive trimming past the requested range.
Reject ranges shorter than s_clustersize instead. That preserves the existing -EINVAL behavior for requests that cannot discard even one allocation unit and keeps zero-cluster trims out of the group walk.
Which versions are affected by CVE-2026-74349?
How do I fix CVE-2026-74349?
Apply the vendor's patch.
Is CVE-2026-74349 being exploited?
There is no known exploitation of CVE-2026-74349 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74349, DEBIAN-CVE-2026-74349, GHSA-xvwx-4pm6-jf3g, UBUNTU-CVE-2026-74349.