Redmine

When an issue description or comment contains a less-than sign (<), this sign is output verbatim in the issue page, instead of being escaped with ampersand-"lt"-semicolon. This causes the issue details page to be invalid XHTML, which is contrary to the page's doctype, and makes it impossible to read the page with an XML parser. I created an issue on the demo site to demonstrate the problem.

To reproduce, run xmllint URL-OF-ISSUE-PAGE, like this:

$ xmllint http://demo.redmine.org/issues/38181
http://demo.redmine.org/issues/38181:166: parser error : StartTag: invalid element name
<p>Hm: <</p>
        ^
http://demo.redmine.org/issues/38181:241: parser error : StartTag: invalid element name
mg alt="Comment" src="/images/comment.png?1286930539" /></a></div><p>And this? <
                                                                               ^
http://demo.redmine.org/issues/38181:330: parser error : Entity 'copy' not defined
    Powered by <a href="http://www.redmine.org/">Redmine</a> &copy; 2006-2010 Je
                                                                   ^

The third error is a false positive (xmllint doesn't know XHTML entities), but the first two errors are symptoms of this problem.