An Improper Check or Handling of Exceptional Conditions vulnerability in the IPsec library of Juniper Networks Junos OS allows a network-based, unauthenticated attacker to cause Denial of Service (DoS). On all MX platforms with MS-MPC or MS-MIC card, when specific IPv4 packets are processed by an IPsec6 tunnel, the Multiservices PIC Management Daemon (mspmand) process will core and restart. This will lead to FPC crash. Traffic flow is impacted while mspmand restarts. Continued receipt of these specific packets will cause a sustained Denial of Service (DoS) condition. This issue only occurs if an IPv4 address is not configured on the multiservice interface. This issue affects: Juniper Networks Junos OS on MX Series All versions prior to 19.4R3-S9; 20.1 version 20.1R3-S5 and later versions; 20.2 versions prior to 20.2R3-S5; 20.3 versions prior to 20.3R3-S5; 20.4 versions prior to 20.4R3-S4; 21.1 versions prior to 21.1R3-S3; 21.2 versions prior to 21.2R3-S1; 21.3 versions prior to 21.3R3; 21.4 versions prior to 21.4R2-S1, 21.4R3; 22.1 versions prior to 22.1R2.