A stack-based buffer overflow exists in Kamailio v6.1.3 and v6.1.4 in the ims_qos_npn module. The w_rx_aar_register() function copies the attacker-controlled host field from the SIP "Via" header into a fixed 46-byte stack buffer without validating its length. An unauthenticated remote attacker can trigger the vulnerability with a crafted SIP "REGISTER" request, causing stack corruption and termination of the affected Kamailio instance, resulting in denial of service.