An Improper Check for Unusual or Exceptional Conditions vulnerability in the kernel of Juniper Network Junos OS on MX Series allows a network based attacker with low privileges to cause a denial of service.

If a scaled configuration for Source class usage (SCU) / destination class usage (DCU) (more than 10 route classes) is present and the SCU/DCU statistics are gathered by executing specific SNMP requests or CLI commands, a 'vmcore' for the RE kernel will be seen which leads to a device restart. Continued exploitation of this issue will lead to a sustained DoS.

This issue only affects MX Series devices with MPC10, MPC11 or LC9600, and MX304. No other MX Series devices are affected.

This issue affects Juniper Networks Junos OS:

• All versions earlier than 20.4R3-S9;
• 21.2 versions earlier than 21.2R3-S6;
• 21.3 versions earlier than 21.3R3-S5;
• 21.4 versions earlier than 21.4R3;
• 22.1 versions earlier than 22.1R3;
• 22.2 versions earlier than 22.2R2;
• 22.3 versions earlier than 22.3R2.