An Improper Check for Unusual or Exceptional Conditions vulnerability in the bbe-smgd of Juniper Networks Junos OS allows an unauthenticated, adjacent attacker to cause a Denial of Service (DoS). In a Broadband Edge / Subscriber Management scenario on MX Series when a specifically malformed ICMP packet addressed to the device is received from a subscriber the bbe-smgd will crash, affecting the subscriber sessions that are connecting, updating, or terminating. Continued receipt of such packets will lead to a sustained DoS condition. When this issue happens the below log can be seen if the traceoptions for the processes smg-service are enabled: BBE_TRACE(TRACE_LEVEL_INFO, "%s: Dropped unsupported ICMP PKT ... This issue affects Juniper Networks Junos OS on MX Series: All versions prior to 19.4R3-S11; 20.2 versions prior to 20.2R3-S7; 20.3 versions prior to 20.3R3-S6; 20.4 versions prior to 20.4R3-S6; 21.1 versions prior to 21.1R3-S4; 21.2 versions prior to 21.2R3-S4; 21.3 versions prior…