Time-of-check Time-of-use (TOCTOU) Race Condition
Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-367
Overtime trend (NVD)
CVSS severity (NVD, All Time)
Per technology (GHSA, All time)
- 29%-Pip
- 24%-Go
- 13%-Maven
- 32%-Others
Short description
Extended description
Best practices to prevent this CWE
Phase: Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Phase: Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Phase: Architecture and Design
Limit the interleaving of operations on files from multiple processes.
Phase: Implementation; Architecture and Design
If you cannot perform operations atomically and you must share access to the resource between multiple processes or threads, then try to limit the amount of time (CPU cycles) between the check and use of the resource. This will not fix the problem, but it could make it more difficult for an attack to succeed.
Phase: Implementation
Recheck the resource after the use call to verify that the action was taken appropriately.
Phase: Architecture and Design
Ensure that some environmental locking mechanism can be used to protect resources effectively.
Phase: Implementation
Ensure that locking occurs before the check, as opposed to afterwards, such that the resource, as checked, is the same as it is when in use.
