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JunosOperating system · Juniper

CVE-2025-30646

MEDIUM · 6.5 CVSS v3.1 Published 2025-04-09
Fix available
A fix is available. Upgrade to 21.2 / 21.4 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
A Signed to Unsigned Conversion Error vulnerability in the Layer 2 Control Protocol daemon (l2cpd) of Juniper Networks Junos OS and Juniper Networks Junos OS Evolved allows an unauthenticated adjacent attacker sending a specifically malformed LLDP TLV to cause the l2cpd process to crash and restart, causing a Denial of Service (DoS).  Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. When an LLDP telemetry subscription is active, receipt of a specifically malformed LLDP TLV causes the l2cpd process to crash and restart. This issue affects: Junos OS: * All versions before 21.2R3-S9,  * from 21.4 before 21.4R3-S10,  * from 22.2 before 22.2R3-S6,  * from 22.4 before 22.4R3-S6,  * from 23.2 before 23.2R2-S3,  * from 23.4 before 23.4R2-S4,  * from 24.2 before 24.2R2;  Junos OS Evolved:  * All versions before 21.4R3-S10-EVO, * from 22.2-EVO before 22.2R3-S6-EVO,  * from 22.4-EVO before 22.4R3-S6-EVO,  * from 23.2-EVO before 23.2R2-S3-EVO,  * from 23.4-EVO before 23.4R2-S4-EVO,  * from 24.2-EVO before 24.2R2-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

A signed to unsigned conversion error in the Layer 2 Control Protocol daemon (l2cpd) of Juniper Networks Junos OS allows an unauthenticated adjacent attacker to send a malformed LLDP TLV that crashes the l2cpd process. When an LLDP telemetry subscription is active, processing this specifically crafted packet causes process restart, and repeated receipt creates a sustained DoS condition.

MitigationApply the vendor-supplied Junos OS patches for the affected versions. If immediate patching is not possible, consider disabling LLDP telemetry subscriptions or implementing 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:< 21.2= 21.2= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2
Junos Os EvolvedOperating system
Affected:< 21.4= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2

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 the Junos OS version
    Run 'show version' or 'request system software version' to get the installed Junos OS version
    Affected if The version matches one of the affected ranges: Junos < 21.2, = 21.2, = 21.4, = 22.2, = 22.4, = 23.2, = 23.4, = 24.2 (or Junos OS Evolved < 21.4, = 21.4, = 22.2, = 22.4, = 23.2, = 23.4, = 24.2)
  2. Verify LLDP is enabled
    Run 'show lldp' or 'show lldp interface' to check LLDP configuration status
    Affected if LLDP is enabled globally or on any interface (LLDP must be running for the attack surface to exist)
  3. Check for active LLDP telemetry subscriptions
    Run 'show lldp statistics' or check telemetry configuration with 'show configuration protocols lldp' and look for telemetry-related entries
    Affected if An LLDP telemetry subscription is actively configured and running (this is required for the vulnerability to be exploitable)
  4. Inspect l2cpd process stability
    Run 'show system processes l2cpd' or check process crash logs with 'show log messages' for recent l2cpd restarts or core dumps
    Affected if The l2cpd process has recently crashed, restarted, or generated core files (indicates possible exploitation attempts)

You are affected if your Junos OS version is in the affected list AND LLDP with an active telemetry subscription is configured, and you are on a network segment where an adjacent unauthenticated attacker can send LLDP packets.

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 21.2 / 21.4 or later
Fixed in 21.221.4
Interim mitigation

Apply the vendor-supplied Junos OS patches for the affected versions. If immediate patching is not possible, consider disabling LLDP telemetry subscriptions or implementing network segmentation to limit adjacent attacker access.

Recommended fix High confidence

For Junos OS: upgrade to 21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S6, 23.2R2-S3, 23.4R2-S4, or 24.2R2 (or later) depending on your version branch. For Junos OS Evolved: upgrade to 21.4R3-S10-EVO, 22.2R3-S6-EVO, 22.4R3-S6-EVO, 23.2R2-S3-EVO, 23.4R2-S4-EVO, or 24.2R2-EVO (or later).

  1. 1. Identify the currently installed Junos OS or Junos OS Evolved version using `show version` command
  2. 2. Determine the appropriate upgrade path based on current version branch (21.2, 21.4, 22.2, 22.4, 23.2, 23.4, or 24.2)
  3. 3. Download the corresponding patched version from Juniper Networks support portal
  4. 4. Upgrade the device using `request system software add <package-name>` command
  5. 5. Reboot the device after upgrade using `request system reboot` command
  6. 6. Verify the l2cpd process is running using `show system processes | match l2cpd`
  7. 7. Confirm the new Junos version is installed using `show version`
Caveat Review Juniper release notes for any compatibility concerns or configuration changes between your current and target version before upgrading.

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
  • Testing2.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,180
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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-2025-30646 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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