The Sifalo Pay WordPress plugin before 2.5.3 does not verify ownership of, or authorisation for, the order being updated when it handles a payment return, allowing unauthenticated attackers to write arbitrary payment session metadata onto any order in the store and to force any order awaiting payment into a failed state.

The Sifalo Pay WordPress plugin before 2.5.3 does not verify ownership of, or authorisation for, the order being updated when it handles a payment return, allowing unauthenticated attackers to write arbitrary payment session metadata onto any order in the store and to force any order awaiting payment into a failed state.