Junos OS (SRX firewalls)
CVE-2024-21618: When LLDP is enabled and a malformed LLDP packet is received, l2cpd crashes
An Access of Memory Location After End of Buffer vulnerability in the Layer-2 Control Protocols Daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause Denial of Service (DoS).
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Junos OS 21.4 | 21.4R3-S4 or later |
| Junos OS 22.1 | 22.1R3-S4 or later |
| Junos OS 22.2 | 22.2R3-S2 or later |
| Junos OS 22.3 | 22.3R2-S2, 22.3R3-S1 or later |
| Junos OS 22.4 | 22.4R3 or later |
| Junos OS 23.2 | 23.2R2 or later |
| Junos OS 0 | Not affected |
| Junos OS Evolved 21.4-EVO | 21.4R3-S5-EVO or later |
| Junos OS Evolved 22.1-EVO | 22.1R3-S4-EVO or later |
| Junos OS Evolved 22.2-EVO | 22.2R3-S2-EVO or later |
| Junos OS Evolved 22.3-EVO | 22.3R2-S2-EVO, 22.3R3-S1-EVO or later |
| Junos OS Evolved 22.4-EVO | 22.4R3-EVO or later |
| Junos OS Evolved 23.2-EVO | 23.2R2-EVO or later |
| Junos OS Evolved 0 | Not affected |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Access of Memory Location After End of Buffer vulnerability in the Layer-2 Control Protocols Daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause Denial of Service (DoS).
On all Junos OS and Junos OS Evolved platforms, when LLDP is enabled on a specific interface, and a malformed LLDP packet is received, l2cpd crashes and restarts. 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:
Junos OS: * from 21.4 before 21.4R3-S4,
- from 22.1 before 22.1R3-S4,
- from 22.2 before 22.2R3-S2,
- from 22.3 before 22.3R2-S2, 22.3R3-S1,
- from 22.4 before 22.4R3,
- from 23.2 before 23.2R2.
Junos OS Evolved: * from 21.4-EVO before 21.4R3-S5-EVO,
- from 22.1-EVO before 22.1R3-S4-EVO,
- from 22.2-EVO before 22.2R3-S2-EVO,
- from 22.3-EVO before 22.3R2-S2-EVO, 22.3R3-S1-EVO,
- from 22.4-EVO before 22.4R3-EVO,
- from 23.2-EVO before 23.2R2-EVO.
This issue does not affect: * Junos OS versions prior to 21.4R1;
- Junos OS Evolved versions prior to 21.4R1-EVO.
Am I affected?
This vulnerability is only exploitable on interfaces with LLDP enabled.
[protocols lldp interface]
Workarounds
There are no available workarounds for this issue.
But if LLDP and its services are not required, customers can disable LLDP.
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.