The CleanTalk WordPress plugin before 6.87 does not prevent unauthenticated, user-supplied comment content from being passed to WordPress's shortcode engine, allowing any visitor to have arbitrary shortcodes registered on the site executed server-side and rendered to every subsequent visitor of the page.

The Spam protection, Honeypot, Anti-Spam by CleanTalk plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content aria-label Placeholder in all versions up to, and including, 6.86 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with custom-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The payload is deliverable via unauthenticated comment submission and executes exclusively for non-logged-in visitors; if comment moderation is enabled, an approving moderator must first publish the comment before the script reaches other users.