Celery 2.1 and 2.2 before 2.2.8, 2.3 before 2.3.4, and 2.4 before 2.4.4 changes the effective id but not the real id during processing of the --uid and --gid arguments to celerybeat, celeryd_detach, celeryd-multi, and celeryev, which allows local users to gain privileges via vectors involving crafted code that is executed by the worker process.