openEQUELLA before 2026.1.0 contains an authenticated remote code execution vulnerability that allows any authenticated non-guest user to execute arbitrary code by exploiting Java deserialization in the HTTP invoker endpoint at /invoker/*. Attackers can bypass the class-name denylist enforced by PluginAwareObjectInputStream by nesting a serialized payload inside a java.security.SignedObject, causing the inner stream to be deserialized by a separate ObjectInputStream that does not apply the denylist, ultimately reaching a JNDI sink and enabling code execution.