CVE-2023-36849: Junos OS and Junos OS Evolved: The l2cpd will crash when a malformed LLDP packet is received

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-07-14 · updated 2026-06-17
Weakness: CWE-703

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 prior to 22.3R2-EVO.

Affected products

Juniper Junos OS: 21.4, 21.4-r1, 21.4-r1-s1, 21.4-r1-s2, 21.4-r2, 21.4-r2-s1 (+20)
Juniper Networks Junos OS Evolved: 21.4, 21.4-r1, 21.4-r1-s1, 21.4-r1-s2, 21.4-r2, 21.4-r2-s1 (+17)

References

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