Cross-site scripting (XSS) vulnerability in spell-check-savedicts.php in the htmlarea SpellChecker module, as used in Serendipity before 1.7.3 and possibly other products, allows remote attackers to inject arbitrary web script or HTML via the to_r_list parameter.
http://www.openwall.com/lists/oss-security/2013/09/01/3
http://www.openwall.com/lists/oss-security/2013/09/01/1
http://www.opensyscom.fr/Actualites/serendipity-xss-vulnerability.html
http://blog.s9y.org/archives/250-Serendipity-1.7.3-released.html