A vulnerability in the SIP ALG packet processing service of Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) to the device by sending specific types of valid SIP traffic to the device. In this case, the flowd process crashes and generates a core dump while processing SIP ALG traffic. Continued receipt of these valid SIP packets will result in a sustained Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS: 12.3X48 versions prior to 12.3X48-D61, 12.3X48-D65 on SRX Series; 15.1X49 versions prior to 15.1X49-D130 on SRX Series; 17.3 versions prior to 17.3R3 on SRX Series; 17.4 versions prior to 17.4R2 on SRX Series.