An Improper Check for Unusual or Exceptional Conditions vulnerability in the the Public Key Infrastructure daemon (pkid) of Juniper Networks Junos OS allows an unauthenticated networked attacker to cause Denial of Service (DoS). The pkid is responsible for the certificate verification. Upon a failed verification, the pkid uses all CPU resources and becomes unresponsive to future verification attempts. This means that all subsequent VPN negotiations depending on certificate verification will fail. This CPU utilization of pkid can be checked using this command:   root@srx> show system processes extensive | match pkid   xxxxx  root  103  0  846M  136M  CPU1  1 569:00 100.00% pkid This issue affects: Juniper Networks Junos OS * All versions prior to 20.4R3-S10; * 21.2 versions prior to 21.2R3-S7; * 21.4 versions prior to 21.4R3-S5; * 22.1 versions prior to 22.1R3-S4; * 22.2 versions prior to 22.2R3-S3; * 22.3 versions prior to 22.3R3-S1; * 22.4 versions prior to 2…