shared/util/StateUtils.java in Apache MyFaces 1.1.x before 1.1.8, 1.2.x before 1.2.9, and 2.0.x before 2.0.1 uses an encrypted View State without a Message Authentication Code (MAC), which makes it easier for remote attackers to perform successful modifications of the View State via a padding oracle attack.

Apache MyFaces 1.1.7 and 1.2.8, as used in IBM WebSphere Application Server and other applications, does not properly handle an unencrypted view state, which allows remote attackers to conduct cross-site scripting (XSS) attacks or execute arbitrary Expression Language (EL) statements via vectors that involve modifying the serialized view object.