AIKIDO-2026-351295

TL;DR

filelock reads a SoftFileLock lock file in its stale-lock detection and PID inspection paths using a symlink-following, unbounded text read. When a lock becomes stale, a local attacker with write access to the lock directory can replace the lock file with a symlink, a FIFO, or an oversized file. A peer process that then reads the lock follows the symlink to an unintended target, blocks indefinitely on the FIFO, or exhausts memory reading the large file, causing denial of service. The fix opens the lock file with O_NOFOLLOW and O_NONBLOCK and caps the read size so hostile replacements are rejected instead of followed.