CVE-2024-21610

/// Technical description

An Improper Handling of Exceptional Conditions vulnerability in the Class of Service daemon (cosd) of Juniper Networks Junos OS allows an authenticated, network-based attacker with low privileges to cause a limited Denial of Service (DoS).

In a scaled CoS scenario with 1000s of interfaces, when specific low privileged commands, received over NETCONF, SSH or telnet, are handled by cosd on behalf of mgd, the respective child management daemon (mgd) processes will get stuck. In case of (Netconf over) SSH this leads to stuck SSH sessions, so that when the connection-limit for SSH is reached, new sessions can't be established anymore. A similar behavior will be seen for telnet etc.

Stuck mgd processes can be monitored by executing the following command:

  user@host> show system processes extensive | match mgd | match sbwait

This issue affects Juniper Networks Junos OS:

* All versions earlier than 20.4R3-S9;

* 21.2 versions earlier than 21.2R3-S7;

* 21.3 versions earlier than 21

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References