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JunosOperating system · Juniper

CVE-2024-21618

MEDIUM · 6.5 CVSS v3.1 Published 2024-04-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
Remediation priority · Elevated
No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A memory access vulnerability exists in the Layer-2 Control Protocols Daemon (l2cpd) in Juniper Networks Junos OS. When LLDP is enabled on an interface and a malformed LLDP packet is received, it triggers an out-of-bounds memory access, causing l2cpd to crash and restart. This causes reinitialization of STP protocols (RSTP, MSTP, VSTP), MVRP, ERP, and affects LLDP-dependent services like PoE and VoIP.

MitigationApply the vendor-provided software updates (21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R3, 23.2R2 or later) to affected devices. As a workaround, disable LLDP on interfaces that do not require it.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2
Junos Os EvolvedOperating system
Affected:= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Junos version
    Execute 'show version' or 'show version detail' on the device CLI to obtain the exact Junos OS or Junos OS Evolved version number
    Affected if The version matches one of the affected releases: 21.4, 22.1, 22.2, 22.3, 22.4, or 23.2 (any minor release within these versions)
  2. Verify LLDP protocol is enabled
    Run 'show lldp interface' or check 'show configuration protocols lldp' to determine whether LLDP is configured on any interface
    Affected if LLDP is enabled on one or more interfaces (the vulnerability only triggers when LLDP is active on an interface)
  3. Check for l2cpd crash events
    Run 'show system crash' or search /var/log/messages for recent l2cpd process restarts, noting any correlation to LLDP packet processing
    Affected if l2cpd has recently crashed or restarted, especially after receiving LLDP traffic on enabled interfaces

A device is affected when running an affected Junos version (21.4, 22.1-22.4, or 23.2) with LLDP enabled on any interface, as malformed LLDP packets on those interfaces can trigger the out-of-bounds memory access in l2cpd.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided software updates (21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R3, 23.2R2 or later) to affected devices. As a workaround, disable LLDP on interfaces that do not require it.

Recommended fix High confidence

Upgrade to the latest available fixed release in your current branch (21.4R3-S4+, 22.1R3-S4+, 22.2R3-S2+, 22.3R2-S2/22.3R3-S1+, 22.4R3+, or 23.2R2+)

  1. 1. Identify the current Junos OS or Junos OS Evolved version using 'show version' command
  2. 2. Based on the current version, determine the appropriate upgrade path to a fixed release:
  3. - For 21.4 branch: upgrade to 21.4R3-S4 or later (21.4R3-S5-EVO for Evolved)
  4. - For 22.1 branch: upgrade to 22.1R3-S4 or later (22.1R3-S4-EVO for Evolved)
  5. - For 22.2 branch: upgrade to 22.2R3-S2 or later (22.2R3-S2-EVO for Evolved)
  6. - For 22.3 branch: upgrade to 22.3R2-S2, 22.3R3-S1 or later (22.3R2-S2-EVO or 22.3R3-S1-EVO for Evolved)
  7. - For 22.4 branch: upgrade to 22.4R3 or later (22.4R3-EVO for Evolved)
  8. - For 23.2 branch: upgrade to 23.2R2 or later (23.2R2-EVO for Evolved)
Caveat Standard Junos upgrade considerations apply - ensure compatibility with existing configurations and review Junos release notes for any potential issues

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation5.0 h
  • Implementation10.0 h
  • Testing6.0 h
  • Review / QA3.0 h
24.0 hours of engineering $4,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-21618 in production — separate from our analysis above.

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