The YOP Poll plugin for WordPress is vulnerable to a race condition in all versions up to, and including, 6.5.26. This is due to improper restrictions on the add() function. This makes it possible for unauthenticated attackers to place multiple votes on a single poll even when the poll is set to one vote per person.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.