An Improper Check or Handling of Exceptional Conditions vulnerability in the processing of a malformed OSPF TLV in Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause the periodic packet management daemon (PPMD) process to go into an infinite loop, which in turn can cause protocols and functions reliant on PPMD such as OSPF neighbor reachability to be impacted, resulting in a sustained Denial of Service (DoS) condition. The DoS condition persists until the PPMD process is manually restarted. This issue affects: Juniper Networks Junos OS: All versions prior to 19.1R3-S9; 19.2 versions prior to 19.2R3-S5; 19.3 versions prior to 19.3R3-S3; 19.4 versions prior to 19.4R3-S9; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S1; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2. Juniper Networks Junos OS Evolved: All versions prior to 20.4R3-S3-EVO; 21.1 versions prior to 21.1R2-EVO.