CVE-2023-36839

Layer 2 service interruption via malformed LLDP packets

Published Oct 12, 2023 · Updated Sep 18, 2024

Input validation in l2cpd in Juniper Networks Junos OS and Junos OS Evolved allows attackers to crash the daemon via LLDP packets. While telemetry polling is active, l2cpd fails to validate a quantity in specifically formed LLDP input before processing it; Juniper has not disclosed the field or operation. An adjacent, unauthenticated sender can interrupt Layer 2 services because the crash reinitializes STP, MVRP, and ERP and disrupts LLDP-dependent functions.

CVSS severity6.5
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Input validation in l2cpd in Juniper Networks Junos OS and Junos OS Evolved allows attackers to crash the daemon via LLDP packets. While telemetry polling is active, l2cpd fails to validate a quantity in specifically formed LLDP input before processing it; Juniper has not disclosed the field or operation. An adjacent, unauthenticated sender can interrupt Layer 2 services because the crash reinitializes STP, MVRP, and ERP and disrupts LLDP-dependent functions.

The record

CVE
CVE-2023-36839
Published
Oct 12, 2023
Updated
Sep 18, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-1284, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <20.4R3-S8-EVO
  2. Affected versionversion=21.1R1-EVO <21.1*-EVO
  3. Affected versionversion=21.2-EVO <21.2R3-S5-EVO
  4. Affected versionversion=21.3-EVO <21.3R3-S4-EVO
  5. Affected versionversion=21.4-EVO <21.4R3-S3-EVO
  6. Affected versionversion=22.1-EVO <22.1R3-S2-EVO
  7. Affected versionversion=22.2-EVO <22.2R3-EVO
  8. Affected versionversion=22.3-EVO <22.3R2-S2-EVO, 22.3R3-EVO
  9. Affected versionversion=22.4-EVO <22.4R1-S1-EVO, 22.4R2-EVO

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=0 <20.4R3-S8-EVO; version=21.1R1-EVO <21.1*-EVO; version=21.2-EVO <21.2R3-S5-EVO; version=21.3-EVO <21.3R3-S4-EVO; version=21.4-EVO <21.4R3-S3-EVO; version=22.1-EVO <22.1R3-S2-EVO; version=22.2-EVO <22.2R3-EVO; version=22.3-EVO <22.3R2-S2-EVO, 22.3R3-EVO; version=22.4-EVO <22.4R1-S1-EVO, 22.4R2-EVO
Juniper Networks · Junos OSversion=0 <20.4R3-S8; version=21.1R1 <21.1*; version=21.2 <21.2R3-S5; version=21.3 <21.3R3-S4; version=21.4 <21.4R3-S3; version=22.1 <22.1R3-S2; version=22.2 <22.2R3; version=22.3 <22.3R2-S2, 22.3R3; version=22.4 <22.4R2

Published CVSS scores

6.5Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1284Improper Validation of Specified Quantity in Input
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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