message/ax/AxMessage.java in OpenID4Java before 0.9.6 final, as used in JBoss Enterprise Application Platform 5.1 before 5.1.2, Step2, Kay Framework before 1.0.2, and possibly other products does not verify that Attribute Exchange (AX) information is signed, which allows remote attackers to modify potentially sensitive AX information without detection via a man-in-the-middle (MITM) attack.