CVE-2025-40205

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The btrfs encode fh() function does not properly account for all cases it handles, potentially leading to an out-of-bounds write. Specifically, when a parent exists and the root ID of the parent and the inode are different, the function may attempt to write BTRFS FID SIZE CONNECTABLE ROOT (40 bytes) to a buffer sized for BTRFS FID SIZE CONNECTABLE (32 bytes), resulting in an 8-byte out-of-bounds write to fid->parent root objectid = parent root id. The issue arises because the function does not always return the correct size to the user, and it fails to validate that max len is large enough before writing data.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.