Open Access Management (OpenAM) is an access management solution. Prior to 16.1.1, the "RADIUS" authentication module opens an unconnected datagram socket and trusts the first UDP datagram received on the client source port. The receive path does not verify the source IP and port, match the response identifier to the outstanding request, or verify the RFC 2865 "Response Authenticator"; the RFC 2869 "Message-Authenticator" is neither sent nor required. Any non-Reject/non-Challenge packet is treated as success. On a deployment with a "RADIUS" module instance enabled on a login chain, an unauthenticated network attacker can race the real server on-path or spray forged "Access-Accept" packets off-path and obtain a session for any "RADIUS"-mapped username without knowing the shared secret. Unlike CVE-2024-3596, exploitation requires no MD5 chosen-prefix forgery because no response authenticator is checked. The resulting session carries the impersonated principal's privileges. This issue is fixed in version 16.1.1.