Pylint: Arbitrary code execution via pickle deserialization of the stats cache in PYLINT_HOME

Impact

Since 2006 / pylint 0.15.2, pylint caches its stats as pickles in PYLINT_HOME and reload them on the next run with pickle.load. Someone without access to the configuration or linted code, but with access to the cache directory (predictable PYLINT_HOME on a multi-user host) can write a crafted pickle that will runs arbitrary code when pylint access its stat cache.

Patches

From pylint 4.0.9, the result cache is now stored as JSON instead of pickle, preventing code-execution.

Workarounds

Until upgrading do not point PYLINT_HOME to an untrusted, shared, or group-writable directory. The default value, ~/.cache/pylint, is writable only by the user running pylint.

Credits

• Reported privately via Tidelift coordinated disclosure (Dan Lenz).