Validate-before-filter vulnerability in cleanhtml.pl 1.129 in LiveJournal CVS before Dec 7 2005 when the cleancss option is enabled allows remote attackers to conduct cross-site scripting (XSS) attacks via a \\\\ (backslash) within a \javascript\ scheme in a style property (such as \javas\\cript\) which bypasses the \javascript\ check before the \\\\ is stripped and then rendered in web browsers that allow scripting in style sheets.