CWE-363: Race Condition Enabling Link Following

The product checks the status of a file or directory before accessing it, which produces a race condition in which the file can be replaced with a link before the access is performed, causing the product to access the wrong file.

While developers might expect that there is a very narrow time window between the time of check and time of use, there is still a race condition. An attacker could cause the product to slow down (e.g. with memory consumption), causing the time window to become larger. Alternately, in some situations, the attacker could win the race by performing a large number of attacks.

Consequences

• Confidentiality, Integrity: Read Files or Directories, Modify Files or Directories

Recent advisories

• GHSA-m462-7rxw-wvpg — filelock: StrictSoftFileLock follows a symbolic link swapped in at <path>.filelock and creates claim files in a directory another local user chooses
• GHSA-crv4-6mhj-j5jh — filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link and hard-links a file of the user running the lock into the lock directory
• GHSA-v4x8-3wr5-3wq8 — filelock ReadWriteLock: SQLite reopens the lock database by name, so a planted symlink or journal file makes the lock user's process overwrite or unlink its own files

All advisories for CWE-363