A deserialization of untrusted data vulnerability has been identified in the ThemeREX Classter WordPress theme that allows PHP object injection attacks. This security flaw affects all versions of the Classter theme from unknown starting version through version 2.5 and earlier. The vulnerability enables attackers to inject malicious PHP objects through untrusted data deserialization processes. Object injection vulnerabilities can lead to remote code execution, privilege escalation, and complete system compromise. WordPress themes are widely deployed making this a significant security concern for affected installations.