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.
thiennv discovered and reported this Cross Site Scripting (XSS) vulnerability in WordPress Private Messages For WordPress Plugin. This could allow a malicious actor to inject malicious scripts, such as redirects, advertisements, and other HTML payloads into your website which will be executed when guests visit your site. This vulnerability has not been known to be fixed yet.