According to the Referral System Rules, mirrors cannot be a target publication. However, the act() function does not ensure that the target publication is not a mirror.
This is currently unexploitable as mirrors cannot be initialized with action modules, therefore the _isActionEnabled check will always revert when called with a mirror. However, this could potentially become exploitable if an attacker finds a way to corrupt the enabledActionModulesBitmap of a mirror publication.
Consider validating that the target publication is not a mirror in act().
