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JunosOperating system · Juniper

CVE-2024-30380

MEDIUM · 6.5 CVSS v3.1 Published 2024-04-16
Fix available
A fix is available. Upgrade to 20.4 / 21.2 or later.
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 Improper Handling of Exceptional Conditions vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows an adjacent unauthenticated attacker to cause a Denial of Service (DoS), which causes the l2cpd process to crash by sending a specific TLV. The l2cpd process is responsible for layer 2 control protocols, such as STP, RSTP, MSTP, VSTP, ERP, and LLDP.  The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP, leading to a Denial of Service.  Continued receipt and processing of this specific TLV will create a sustained Denial of Service (DoS) condition. This issue affects: Junos OS: all versions before 20.4R3-S9, from 21.2 before 21.2R3-S7, from 21.3 before 21.3R3-S5, 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 22.4R2-S2, 22.4R3, from 23.2 before 23.2R1-S1, 23.2R2; Junos OS Evolved: all versions before 21.2R3-S7, from 21.3 before 21.3R3-S5-EVO, from 21.4 before 21.4R3-S5-EVO, from 22.1 before 22.1R3-S4-EVO, from 22.2 before 22.2R3-S2-EVO, from 22.3 before 22.3R2-S2-EVO, 22.3R3-S1-EVO, from 22.4 before 22.4R2-S2-EVO, 22.4R3-EVO, from 23.2 before 23.2R1-S1-EVO, 23.2R2-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

An adjacent unauthenticated attacker can send a specific TLV that triggers improper exception handling in the l2cpd process (layer 2 control protocol daemon), causing it to crash. The l2cpd crash forces reinitialization of STP protocols (RSTP, MSTP, VSTP), MVRP, and ERP, resulting in denial of service. Continued receipt of the malformed TLV creates a sustained DoS condition.

MitigationApply vendor-supplied Junos OS/Evolved patches to the fixed versions specified in the advisory (20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S2/22.4R3, 23.2R1-S1/23.2R2 or later). Consider network segmentation to limit adjacent attacker access.

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:< 20.4= 20.4= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2
Junos Os EvolvedOperating system
Affected:< 21.2= 21.2= 21.3= 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 Junos product type
    Run 'show version' and look for 'Junos' vs 'Junos OS Evolved' in the OS description
    Affected if Product is Junos or Junos OS Evolved but version is not in the fixed releases (20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S2/22.4R3, 23.2R1-S1/23.2R2 or later)
  2. Confirm installed version
    Run 'show version' and match the exact version number (e.g., 22.1, 22.2, 22.3, 22.4, 23.2) against the affected version list in the CVE
    Affected if Version matches any of these: Junos < 20.4; = 20.4; = 21.2; = 21.3; = 21.4; = 22.1; = 22.2; = 22.3; = 22.4; = 23.2 OR Junos OS Evolved < 21.2; = 21.2; = 21.3; = 21.4; = 22.1; = 22.2; = 22.3; = 22.4; = 23.2
  3. Verify l2cpd process is running
    Run 'show system processes' or 'ps aux | grep l2cpd' to check if the layer 2 control protocol daemon is active
    Affected if l2cpd process is running on a vulnerable version
  4. Check if STP/MVRP/ERP protocols are enabled
    Run 'show protocols' to list active protocols; look for rstp, mstp, vstp, mvrp, or erp statements in configuration via 'show configuration protocols'
    Affected if Any of RSTP, MSTP, VSTP, MVRP, or ERP protocols are enabled on the device

Environment is affected if running a vulnerable Junos/Junos OS Evolved version with l2cpd process active and at least one of RSTP/MSTP/VSTP/MVRP/ERP protocol enabled.

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
Upgrade available Upgrade to 20.4 / 21.2 or later
Fixed in 20.421.2
Interim mitigation

Apply vendor-supplied Junos OS/Evolved patches to the fixed versions specified in the advisory (20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S2/22.4R3, 23.2R1-S1/23.2R2 or later). Consider network segmentation to limit adjacent attacker access.

Recommended fix High confidence

Upgrade to a fixed version: 20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S2/22.4R3, 23.2R1-S1/23.2R2 or later for Junos OS (or -EVO equivalents for Junos OS Evolved)

  1. 1. Identify the current Junos OS or Junos OS Evolved version installed on the device using 'show version' command.
  2. 2. Review the fixed versions listed in the official Juniper advisory for the appropriate release train (20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S2/22.4R3, 23.2R1-S1/23.2R2 for Junos OS, or equivalent -EVO versions for Junos OS Evolved).
  3. 3. Plan maintenance window as the upgrade will require a system reboot.
  4. 4. Back up the current configuration using 'request system configuration backup' or manual configuration export.
  5. 5. Download the appropriate fixed Junos software image from the Juniper Networks support portal.
  6. 6. Install the software update using 'request system software add <package_name>' command.
  7. 7. Reboot the system using 'request system reboot' command.
  8. 8. After reboot, verify the new version is running with 'show version' and confirm l2cpd process stability with 'show system processes l2cpd'.
Caveat Standard Junos upgrade risks apply - ensure configuration compatibility, plan for downtime, and verify feature support in the target release

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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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-2024-30380 in production — separate from our analysis above.

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What belongs here
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