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JunosOperating system · Juniper

CVE-2022-22172

MEDIUM · 6.5 CVSS v3.1 Published 2022-01-19
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
A Missing Release of Memory after Effective Lifetime vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a memory leak. Continued exploitation can lead to memory exhaustion and thereby a Denial of Service (DoS). This issue occurs when specific LLDP packets are received. The impact of the l2cpd cores is that if any of the stp protocols (rstp, mstp or vstp) is used then stp re-converges and traffic loss will occur during that time. Also if any services depend on LLDP state (like PoE or VoIP device recognition) then these will also be affected. The memory utilization of the L2CPd process can be monitored with the following command: user@host> show system processes extensive | match l2cpd 1234 root 52 0 521M 43412K RUN 1 4:02 34.47% l2cpd This issue affects: Juniper Networks Junos OS 18.4 version 18.4R2-S4 and later versions prior to 18.4R2-S10. 19.2 versions prior to 19.2R1-S8, 19.2R3-S4; 19.3 versions prior to 19.3R3-S5; 19.4 versions prior to 19.4R3-S7; 20.1 versions prior to 20.1R3-S3; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2-S2, 21.1R3; 21.2 versions prior to 21.2R2; Juniper Networks Junos OS Evolved All versions prior to 20.4R3-S2-EVO; 21.1 version 21.1R1-EVO and later versions; 21.2 versions prior to 21.2R2-EVO. This issue does not affect: Juniper Networks Junos OS 19.1 version 19.1R1 and later versions.

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 missing memory release vulnerability in the Layer-2 control protocols daemon (l2cpd) allows an unauthenticated adjacent attacker to cause a memory leak by sending specific LLDP packets. Continued exploitation leads to memory exhaustion, causing DoS. When STP protocols are in use, this triggers re-convergence and traffic loss.

MitigationApply the applicable Juniper security update for your Junos OS or Junos OS Evolved version as listed in the advisory. Until patched, monitor l2cpd memory usage and consider disabling LLDP if not required.

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:= 18.4= 19.2= 19.3= 19.4= 20.1= 20.2= 20.3= 20.4= 21.1= 21.2
Junos Os EvolvedOperating system
Affected:= 20.4= 21.1= 21.2

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 OS version
    Run 'show version' or check system version to determine if the installed version matches any of these: 18.4, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3, 20.4, 21.1, 21.2
    Affected if The installed Junos version matches any of the listed affected versions
  2. Confirm l2cpd daemon is running
    Check the status of the l2cpd process using system process monitoring commands
    Affected if The l2cpd process is active on the device
  3. Determine if LLDP is enabled
    Check LLDP configuration using 'show lldp' or review the interface configurations where LLDP is enabled
    Affected if LLDP is enabled on any interface
  4. Verify if STP protocols are in use
    Check for STP, RSTP, or MSTP configuration using 'show spanning-tree' or review protocol settings
    Affected if Any Spanning Tree Protocol (STP/RSTP/MSTP) is configured and active

The device is affected if it runs a vulnerable Junos version (18.4 through 21.2), has l2cpd running, and has LLDP enabled; STP usage amplifies the impact but is not required for the vulnerability to exist.

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 applicable Juniper security update for your Junos OS or Junos OS Evolved version as listed in the advisory. Until patched, monitor l2cpd memory usage and consider disabling LLDP if not required.

Recommended fix High confidence

Upgrade to Junos OS 18.4R2-S10 / 19.2R1-S8 / 19.2R3-S4 / 19.3R3-S5 / 19.4R3-S7 / 20.1R3-S3 / 20.2R3-S2 / 20.3R3-S1 / 20.4R3 / 21.1R2-S2 / 21.1R3 / 21.2R2 or later; or Junos OS Evolved 20.4R3-S2-EVO / 21.2R2-EVO or later

  1. 1. Identify the currently running Junos OS or Junos OS Evolved version using: show version
  2. 2. Determine if your current version is affected by checking against the vulnerable versions listed (18.4R2-S4 through 18.4R2-S9, 19.2 versions before 19.2R1-S8/19.2R3-S4, 19.3 before 19.3R3-S5, 19.4 before 19.4R3-S7, etc.)
  3. 3. For Junos OS: upgrade to one of the fixed releases: 18.4R2-S10, 19.2R1-S8, 19.2R3-S4, 19.3R3-S5, 19.4R3-S7, 20.1R3-S3, 20.2R3-S2, 20.3R3-S1, 20.4R3, 21.1R2-S2, 21.1R3, 21.2R2, or later
  4. 4. For Junos OS Evolved: upgrade to 20.4R3-S2-EVO, 21.2R2-EVO, or later
  5. 5. After upgrade, monitor l2cpd process memory usage with: show system processes extensive | match l2cpd
  6. 6. Verify the fix is applied by confirming the l2cpd process memory remains stable after receiving LLDP packets
Caveat Standard Junos upgrade precautions apply - review release notes for any compatibility notes, and schedule maintenance window as upgrade will require system reload

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

Fix this in Junos Scoped from the published advisory
  • Consultation6.0 h
  • Implementation2.0 h
  • Testing8.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,480
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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-2022-22172 in production — separate from our analysis above.

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