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Junos Os EvolvedOperating system · Juniper

CVE-2024-39519

MEDIUM · 6.5 CVSS v3.1 Published 2024-07-11
Fix available
A fix is available. Upgrade to 22.4 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
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS Evolved on ACX7000 Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS). On all ACX 7000 Series platforms running Junos OS Evolved, and configured with IRBs, if a Customer Edge device (CE) device is dual homed to two Provider Edge devices (PE) a traffic loop will occur when the CE sends multicast packets. This issue can be triggered by IPv4 and IPv6 traffic. This issue affects Junos OS Evolved:  All versions from 22.2R1-EVO and later versions before 22.4R2-EVO, This issue does not affect Junos OS Evolved versions before 22.1R1-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

Improper check for unusual conditions in the Packet Forwarding Engine of Juniper Networks Junos OS Evolved on ACX7000 Series allows an unauthenticated, adjacent attacker to cause a traffic loop and DoS when a dual-homed Customer Edge device sends multicast packets in an IRB-configured network environment.

MitigationUpgrade Junos OS Evolved on ACX7000 Series to version 22.4R2-EVO or later. As an interim measure, consider disabling multicast routing or implementing loop prevention mechanisms at the CE-PE interface level.

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
Junos Os EvolvedOperating system
Affected:>= 22.2, < 22.4= 22.4

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 device model
    Run 'show chassis hardware' or check the device model to confirm it is an ACX7000 Series device
    Affected if Device is not an ACX7000 Series (vulnerability only affects ACX7000)
  2. Check Junos OS Evolved version
    Run 'show version' to identify the installed Junos OS Evolved version
    Affected if Version is 22.2, 22.3, 22.4, or any version >= 22.2 and < 22.4R2-EVO (including 22.4 exactly)
  3. Verify IRB configuration exists
    Run 'show configuration interfaces irb' or 'show configuration routing-instances' to check if IRB interfaces are configured
    Affected if IRB interfaces are configured in the network environment
  4. Confirm multicast routing is enabled
    Run 'show configuration protocols pim' or 'show configuration routing-options multicast' to check if multicast protocols (PIM) or multicast routing are enabled
    Affected if Multicast routing or PIM is enabled on the device
  5. Check for dual-homed CE topology
    Review network topology and run 'show configuration protocols bgp' or 'show lacp' to identify if there is a dual-homed Customer Edge device connected to the ACX7000
    Affected if A dual-homed CE device exists sending multicast traffic in the IRB network

User is affected if running Junos OS Evolved on ACX7000 Series versions 22.2 through 22.4 with IRB configured, multicast routing enabled, and a dual-homed CE device in the network topology.

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 22.4 or later
Fixed in 22.4
Interim mitigation

Upgrade Junos OS Evolved on ACX7000 Series to version 22.4R2-EVO or later. As an interim measure, consider disabling multicast routing or implementing loop prevention mechanisms at the CE-PE interface level.

Recommended fix High confidence

22.4R2-EVO or later

  1. Upgrade Junos OS Evolved on ACX7000 Series devices to version 22.4R2-EVO or later
  2. After upgrade, verify the IRB configuration and dual-homing setup is functioning correctly
  3. Monitor for any traffic loop issues with multicast IPv4/IPv6 traffic
  4. Review release notes for any additional migration or compatibility notes

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

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2024-39519 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data