There's a bug that enables a cross-site scripting vulnerability in independent_publisher_replytocom(). If a post page is viewed with something like ?replytocom=42<fnord/> appended to the URL the <fnord/> will be output verbatim into the resulting HTML, which could end very badly, if more evil HTML code was inserted.
The shortest fix is to just cast the ID to integer, since it's a number, and that will remove any injected code. In general though: Every time you echo in PHP, you should be absolutely certain that nothing bad can happen. There may be other instances of this in the code, I didn't look and only found this one by accident.
Fix an XSS in independent_publisher_replytocom()
@henryk Merged. Thank you! I'm not sure how I missed that one. I'm going through the whole codebase right now to see if I missed any others like this. Cheers!
I reviewed all 95 echo statements in the codebase. Everything else looks good. :-)