An Improper Handling of Undefined Values vulnerability in the periodic packet management daemon (PPMD) of Juniper Networks Junos OS on MX Series(except MPC10, MPC11 and LC9600) allows an unauthenticated adjacent attacker to cause a Denial of Service (DoS). When a malformed CFM packet is received, it leads to an FPC crash. Continued receipt of these packets causes a sustained denial of service.

This vulnerability occurs only when CFM has been configured on the interface. This issue affects Juniper Networks Junos OS: versions prior to 19.1R3-S10 on MX Series; 19.2 versions prior to 19.2R3-S7 on MX Series; 19.3 versions prior to 19.3R3-S8 on MX Series; 19.4 versions prior to 19.4R3-S12 on MX Series; 20.1 version 20.1R1 and later versions on MX Series; 20.2 versions prior to 20.2R3-S8 on MX Series; 20.3 version 20.3R1 and later versions on MX Series; 20.4 versions prior to 20.4R3-S7 on MX Series; 21.1 versions prior to 21.1R3-S5 on MX Series; 21.2 versions prior to 21.2R3-S5 on MX Series; 21.3 versions prior to 21.3R3-S4 on MX Series; 21.4 versions prior to 21.4R3-S4 on MX Series; 22.1 versions prior to 22.1R3-S3 on MX Series; 22.2 versions prior to 22.2R3-S1 on MX Series; 22.3 versions prior to 22.3R3 on MX Series; 22.4 versions prior to 22.4R1-S2, 22.4R2 on MX Series.