Deactivate and delete. This plugin has been closed as of May 20, 2022 and is not available for download. This closure is temporary, pending a full review.
FearZzZz discovered and reported this Cross Site Request Forgery (CSRF) vulnerability in WordPress Private Messages For WordPress Plugin. This could allow a malicious actor to force higher privileged users to execute unwanted actions under their current authentication. This vulnerability has not been known to be fixed yet.