Mako before 0.3.4 relies on the cgi.escape function in the Python standard library for cross-site scripting (XSS) protection, which makes it easier for remote attackers to conduct XSS attacks via vectors involving single-quote characters and a JavaScript onLoad event handler for a BODY element.
http://www.makotemplates.org/CHANGES
http://secunia.com/advisories/39935
http://lists.opensuse.org/opensuse-security-announce/2010-08/msg00001.html