pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev101, Api.check_apikey caches successful validation in self._apikey_cache using only the attacker-controlled key_id. After a legitimate key populates the cache, a forged API key with the same key_id reaches the cache-hit path without comparing apikey[-43:] to the stored hash through hmac.compare_digest. Key identifiers are small sequential integers, so an unauthenticated remote attacker can enumerate an active identifier and inherit the cached key owner's permissions during the 300-second cache lifetime. This issue is fixed in version 0.5.0b3.dev101.