International Components for Unicode (ICU) 4.0 3.6 and other 3.x versions as used in Apple Mac OS X 10.5 before 10.5.7 iPhone OS 1.0 through 2.2.1 iPhone OS for iPod touch 1.1 through 2.2.1 Fedora 9 and 10 and possibly other operating systems does not properly handle invalid byte sequences during Unicode conversion which might allow remote attackers to conduct cross-site scripting (XSS) attacks.