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 to 22.4R2;
Juniper Networks Junos OS Evolved
All versions prior to 20.4R3-S8-EVO;
21.1 version 21.1R1-EVO and later versions;
21.2 versions prior to 21.2R3-S5-EVO;
21.3 versions prior to 21.3R3-S4-EVO;
21.4 versions prior to 21.4R3-S3-EVO;
22.1 versions prior to 22.1R3-S2-EVO;
22.2 versions prior to 22.2R3-EVO;
22.3 versions prior to 22.3R2-S2-EVO;
22.4 versions prior to 22.4R1-S1-EVO;
This vulnerability is only exploitable on interfaces with LLDP enabled. LLDP can be configured with the following command:[protocols lldp interface <interface>]
[protocols lldp interface <interface>]
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
This issue was seen during production usage.
This issue has been assigned CVE-2023-36839.
The following software releases have been updated to resolve this specific issue:
Junos OS: 20.4R3-S8, 21.2R3-S5, 21.3R3-S4, 21.4R3-S3, 22.1R3-S2, 22.2R3, 22.3R2-S2, 22.3R3, 22.4R2, 23.2R1, and all subsequent releases.
Junos OS Evolved: 20.4R3-S8-EVO, 21.2R3-S5-EVO, 21.3R3-S4-EVO, 21.4R3-S3-EVO, 22.1R3-S2-EVO, 22.2R3-EVO, 22.3R2-S2-EVO, 22.3R3-EVO, 22.4R1-S1-EVO, 22.4R2-EVO, 23.1R1-EVO, 23.1R2-EVO, 23.2R1-EVOThis issue is being tracked as PR 1712287 which is visible on the Customer Support website.
Note: Juniper SIRT's policy [juniper.net] is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).
If LLDP and its services are not required, customers can disable LLDP. Disabling telemetry polling also mitigates the issue.
There are no other known workarounds for this issue.
2023-10-11: Initial Publication