The Webmention plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to and including 5.8.0 via parser-derived 'avatar' and 'url' author metadata.
The Webmention plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 5.6.2 in the 'MF2::parse_authorpage' function via the 'Receiver::post' function.
The Webmention plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 5.6.2 via the 'Tools::read' function.
The Webmention plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Open Graph og:title meta tag of a webmention source URL in versions up to, and including, 5.10.1.