A denial of service vulnerability exists in Steamworks game clients and servers using P2P authentication. When processing the ValidateAuthTicketResponse_t callback, if the m_eAuthSessionResponse field is set to k_EAuthSessionResponseAuthTicketNetworkIdentityFailure, the system panics. This occurs if a malicious client sends an authentication ticket with a network identity that does not match the verifier's identity. This affects versions prior to 0.13.1 and has been fixed in version 0.13.1.