CVE-2023-36839

/// Technical description

An Improper Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS).

This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. 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.

This issue affects:

Juniper Networks Junos OS

* All versions prior to 20.4R3-S8;

* 21.1 version 21.1R1 and later versions;

* 21.2 versions prior to 21.2R3-S5;

* 21.3 versions prior to 21.3R3-S4;

* 21.4 versions prior to 21.4R3-S3;

* 22.1 versions prior to 22.1R3-S2;

* 22.2 versions prior to 22.2R3;

* 22.3 versions prior to 22.3R2-S2;

* 22.4 versions prior

/// 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