CVE-2025-68266 bfs: Reconstruct file type when loading from disk
A flaw in the Linux kernel's BFS filesystem allows attackers to cause memory corruption or denial of service by mounting a maliciously crafted filesystem image.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68266?
CVE-2025-68266 is a memory corruption vulnerability in Linux, published on 16 Dec 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:
bfs: Reconstruct file type when loading from disk
syzbot is reporting that S_IFMT bits of inode->i_mode can become bogus when the S_IFMT bits of the 32bits "mode" field loaded from disk are corrupted or when the 32bits "attributes" field loaded from disk are corrupted.
A documentation says that BFS uses only lower 9 bits of the "mode" field. But I can't find an explicit explanation that the unused upper 23 bits (especially, the S_IFMT bits) are initialized with 0.
Therefore, ignore the S_IFMT bits of the "mode" field loaded from disk. Also, verify that the value of the "attributes" field loaded from disk is either BFS_VREG or BFS_VDIR (because BFS supports only regular files and the root directory).
Which versions are affected by CVE-2025-68266?
How do I fix CVE-2025-68266?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-68266 being exploited?
There is no known exploitation of CVE-2025-68266 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-68266, DEBIAN-CVE-2025-68266, GHSA-cf7w-xh8m-r378, ROOT-OS-DEBIAN-11-CVE-2025-68266, ROOT-OS-DEBIAN-12-CVE-2025-68266, ROOT-OS-DEBIAN-13-CVE-2025-68266 and 3 more.