CVE-2023-36849

/// Technical description

An Improper Check or Handling of Exceptional Conditions vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a Denial of Service (DoS).

When a malformed LLDP packet is received, l2cpd will crash and restart. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected. Continued receipt of such packets will lead to a sustained Denial of Service.

This issue affects:

Juniper Networks Junos OS

21.4 versions prior to 21.4R3-S3;

22.1 versions prior to 22.1R3-S3;

22.2 versions prior to 22.2R2-S1, 22.2R3;

22.3 versions prior to 22.3R2.

Juniper Networks Junos OS Evolved

21.4-EVO versions prior to 21.4R3-S2-EVO;

22.1-EVO versions prior to 22.1R3-S3-EVO;

22.2-EVO versions prior to 22.2R2-S1-EVO, 22.2R3-EVO;

22.3-EVO versions

/// 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