Junos OS: MX Series and SRX Series: The flow processing daemon (flowd) will crash if the SIP ALG is enabled and specific SIP messages are processed

An Improper Locking vulnerability in the SIP ALG of Juniper Networks Junos OS on MX Series with MS-MPC or MS-MIC card and SRX Series allows an unauthenticated, network-based attacker to cause a flow processing daemon (flowd) crash and thereby a Denial of Service (DoS). Continued receipt of these specific packets will cause a sustained Denial of Service condition. This issue occurs when SIP ALG is enabled and specific SIP messages are processed simultaneously. This issue affects: Juniper Networks Junos OS on MX Series and SRX Series 20.4 versions prior to 20.4R3-S4; 21.1 versions prior to 21.1R3-S3; 21.2 versions prior to 21.2R3-S2; 21.3 versions prior to 21.3R3; 21.4 versions prior to 21.4R3; 22.1 versions prior to 22.1R2. This issue does not affect Juniper Networks Junos OS versions prior to 20.4R1 on MX Series, or SRX Series.