Out-of-Bounds Write in Linux Kernel Btrfs File System

CVE-2025-40205

What is CVE-2025-40205?

A potential out-of-bounds write vulnerability exists in the btrfs_encode_fh() function of the Linux kernel. This issue arises due to improper handling of certain parameters, which could lead to memory corruption if the size of the buffer is not sufficiently allocated. Specifically, when a parent directory is involved and its root ID differs from that of the inode, the function may attempt to write more data than allocated. Although not easily triggered, this issue poses a risk that warrants attention and has been addressed in a recent patch ensuring appropriate size validation before writing.

References