Loading the blog page with an invalid post name results in a comment box being displayed to all users above the list of posts. Authenticated users may submit comments to this which are stored and displayed in the list of blog posts. All invalid 'name' parameter submissions appear to affect a single comment thread which is displayed on any page with an invalid name given.
Evidence and steps to reproduce provided to @1N3 via Slack.
Check for valid ?name parameter before displaying the comment box or accepting comment submissions. As a sanity check, check database regularly for orphaned comments.Screenshot: