dbcve.org
JunosOperating system · Juniper

CVE-2024-21596

MEDIUM · 5.3 CVSS v3.1 Published 2024-01-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable 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 Heap-based Buffer Overflow vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network based attacker to cause a Denial of Service (DoS). If an attacker sends a specific BGP UPDATE message to the device, this will cause a memory overwrite and therefore an RPD crash and restart in the backup Routing Engine (RE). Continued receipt of these packets will cause a sustained Denial of Service (DoS) condition in the backup RE. The primary RE is not impacted by this issue and there is no impact on traffic. This issue only affects devices with NSR enabled. Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability. This issue requires an attacker to have an established BGP session to a system affected by the issue. This issue affects both eBGP and iBGP implementations. This issue affects: Juniper Networks Junos OS * All versions earlier than 20.4R3-S9; * 21.2 versions earlier than 21.2R3-S7; * 21.3 versions earlier than 21.3R3-S5; * 21.4 versions earlier than 21.4R3-S5; * 22.1 versions earlier than 22.1R3-S4; * 22.2 versions earlier than 22.2R3-S2; * 22.3 versions earlier than 22.3R3-S1; * 22.4 versions earlier than 22.4R2-S2, 22.4R3; * 23.1 versions earlier than 23.1R2; * 23.2 versions earlier than 23.2R1-S2, 23.2R2. Juniper Networks Junos OS Evolved * All versions earlier than 21.3R3-S5-EVO; * 21.4-EVO versions earlier than 21.4R3-S5-EVO; * 22.1-EVO versions earlier than 22.1R3-S4-EVO; * 22.2-EVO versions earlier than 22.2R3-S2-EVO; * 22.3-EVO versions later than 22.3R1-EVO; * 22.4-EVO versions earlier than 22.4R2-S2-EVO, 22.4R3-EVO; * 23.1-EVO versions earlier than 23.1R2-EVO; * 23.2-EVO versions earlier than 23.2R1-S2-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

Heap-based buffer overflow in Juniper RPD when processing specially crafted BGP UPDATE messages. An attacker with an established BGP session can trigger memory corruption causing RPD crash/restart on the backup Routing Engine. Only affects devices with NSR (Non-Stop Routing) enabled; primary RE and SRX series are unaffected.

MitigationApply Junos OS patches per the version matrix (22.4R3+, 23.2R2+, etc.) or disable NSR if operationally feasible. Since an established BGP session is required, ensure BGP peers are trusted and consider BGP route validation/filtering.

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= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4= 23.1= 23.2
Junos Os EvolvedOperating system
Affected:= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4= 23.1= 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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

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 device platform and confirm it is not SRX
    Run 'show version' or 'show chassis hardware' to verify the device is a Juniper MX, PTX, or EX series router (not SRX firewall). SRX series are unaffected.
    Affected if Device is an SRX series firewall (unaffected platform)
  2. Check installed Junos version
    Run 'show version' and compare the installed version to the affected ranges: Junos 20.4, 21.2-21.4, 22.1-22.4, 23.1-23.2 or Junos OS Evolved 21.3-21.4, 22.1-22.4, 23.1-23.2.
    Affected if Installed version matches one of the listed affected versions
  3. Verify if NSR is enabled
    Run 'show routing-processes' or 'show system processes extensive | grep nsr' to determine if Non-Stop Routing is currently enabled on the device.
    Affected if NSR is enabled - this is required for the vulnerability to be exploitable
  4. Confirm device has redundant Routing Engines
    Run 'show chassis redundancy' to verify the presence of a backup Routing Engine. The flaw only affects the backup RE; devices with a single RE are not impacted.
    Affected if Device has a backup Routing Engine and NSR is enabled

A user is affected if they are running an affected Junos version on an MX/PTX/EX router with NSR enabled and a redundant backup Routing Engine present.

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 Junos OS patches per the version matrix (22.4R3+, 23.2R2+, etc.) or disable NSR if operationally feasible. Since an established BGP session is required, ensure BGP peers are trusted and consider BGP route validation/filtering.

Recommended fix High confidence

20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S2, 22.3R3-S1, 22.4R2-S2, 22.4R3, 23.1R2, or 23.2R1/23.2R2 for Junos OS (or Evolved equivalents)

  1. 1. Verify that NSR (Non-Stop Routing) is enabled on the device by running 'show chassis redundancy' and checking the NSR status.
  2. 2. Identify the current Junos OS or Junos OS Evolved version by running 'show version'.
  3. 3. For Junos OS devices: upgrade to one of the fixed releases: 20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S2, 22.3R3-S1, 22.4R2-S2, 22.4R3, 23.1R2, or 23.2R1-S2/23.2R2 (or later).
  4. 4. For Junos OS Evolved devices: upgrade to one of the fixed releases: 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S2-EVO, 22.4R2-S2-EVO, 22.4R3-EVO, 23.1R2-EVO, or 23.2R1-S2-EVO/23.2R2-EVO (or later).
  5. 5. After upgrade, verify the fix by confirming the new Junos version is running and NSR is operational using 'show chassis redundancy'.
  6. 6. Implement BGP filtering or routing policies to limit BGP UPDATE messages from untrusted peers as an additional interim mitigation until upgrade is complete.
Caveat Standard Junos upgrade considerations apply - review release notes for potential changes to routing protocols, HA features, and ensure compatibility with existing network topology. NSR functionality should be tested post-upgrade.

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,600
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,160.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2024-21596 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2024-21596 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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