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Junos OS and Junos OS Evolved: Stack-based buffer overflow in l2cpd LLDP processing

CVE-2026-102050High 8.7

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Summary

A stack-based buffer overflow in the l2cpd daemon of Junos OS and Junos OS Evolved can be triggered by LLDP packets. An unauthenticated attacker on the same Layer 2 network segment (adjacent network) can cause a denial of service in Layer 2 control-plane processing. Interfaces must have LLDP configured for the attack to work, and repeated triggering may disrupt LLDP and other Layer 2 control protocols across the device.

Affected

  • Junos OS: versions before 23.2R2-S7.7, 23.4 before 23.4R2-S8.13, 24.2 before 24.2R2-S5.5, 24.4 before 24.4R2-S5, 25.2 before 25.2R2-S2, 25.4 before 25.4R1-S3, 26.2 before 26.2R1-S2
  • Junos OS Evolved: versions before 23.2R2-S7.7-EVO, 23.4 before 23.4R2-S8.11-EVO, 24.2 before 24.2R2-S5.6-EVO, 24.4 before 24.4R2-S5-EVO, 25.2 before 25.2R2-S2-EVO, 25.4 before 25.4R1-S3-EVO, 26.2 before 26.2R1-S2-EVO
  • Platforms 23.4X100, 25.2X100 (before 25.2X100-D35-EVO) and 25.4X300 (before 25.4X300-D40-EVO) are listed as affected by third-party data; fixed release for 23.4X100 unknown
  • Required configuration: protocols lldp interface <interface>

Fixed in

  • Junos OS: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1 and all later releases
  • Junos OS Evolved: 23.2R2-S7.7-EVO, 23.4R2-S8.11-EVO, 24.2R2-S5.6-EVO, 24.4R2-S5-EVO, 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4R2-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO, 26.2R2-EVO, 26.4R1-EVO and all later releases
  • Confirm the exact release for each platform in JSA112187

Workaround

  • Disable LLDP on interfaces where it is not required (protocols lldp interface)
  • No other vendor workaround identified

Exploitation

  • Juniper SIRT is not aware of any malicious exploitation
  • Not listed in CISA KEV according to third-party data
  • CISA SSVC: exploitation none, not automatable, total technical impact
  • No public proof of concept found in research; this does not prove none exists

Our recommendation

  • Inventory Junos OS and Junos OS Evolved devices and check whether LLDP is enabled on any interface
  • Patch affected devices in the next maintenance window, prioritising devices with LLDP enabled in shared or poorly segmented VLANs
  • Disable LLDP on interfaces that do not need it until patching is complete
  • Check whether Unified Access Policy is used, because sibling CVE-2026-102049 affects the same daemon and should be prioritised
  • Verify fixed versions and affected platforms in JSA112187 before rollout
  • Monitor for repeated LLDP-related errors, daemon restarts or Layer 2 instability

Public exploits

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 03:15.

Original description (NVD)

A Stack-based Buffer Overflow vulnerability in the l2cpd daemon of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a denial of service in Layer 2 control-plane processing via LLDP packets received on an interface configured for LLDP. Repeated triggering may disrupt LLDP and other Layer 2 control protocols across the device.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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