rtMedia for WordPress, BuddyPress and bbPress < 4.7.12 - Subscriber+ Arbitrary Activity Privacy Modification via IDOR

The rtMedia for WordPress, BuddyPress and bbPress WordPress plugin before 4.7.12 does not check ownership before changing the privacy level of an activity and its attached media, relying only on a nonce shared with every logged-in user, allowing users with a subscriber-level account or above to make another user's private activity public or hide it.