Impact

Since 2006 / pylint 0.15.2, pylint caches its stats as pickles in PYLINTHOME 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 PYLINTHOME 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 PYLINTHOME 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).