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JunosOperating system · Juniper

CVE-2023-44199

HIGH · 7.5 CVSS v3.1 Published 2023-10-13
Fix available
A fix is available. Upgrade to 20.4 or later.
See remediation →
84/100
Remediation priority · High
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
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series allows a network-based, unauthenticated attacker to cause a Denial of Service (DoS). On Junos MX Series platforms with Precision Time Protocol (PTP) configured, a prolonged routing protocol churn can lead to an FPC crash and restart. This issue affects Juniper Networks Junos OS on MX Series: * All versions prior to 20.4R3-S4; * 21.1 version 21.1R1 and later versions; * 21.2 versions prior to 21.2R3-S2; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3; * 22.1 versions prior to 22.1R3; * 22.2 versions prior to 22.2R1-S1, 22.2R2.

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 vulnerability in the Packet Forwarding Engine (PFE) of Juniper MX Series routers running Junos OS allows an unauthenticated network attacker to cause FPC crashes and restarts by triggering prolonged routing protocol churn when Precision Time Protocol (PTP) is configured. The issue stems from improper handling of unusual or exceptional conditions.

MitigationUpgrade Junos OS to a fixed version (20.4R3-S4, 21.1R1+, 21.2R3-S2, 21.3R3-S5, 21.4R3, 22.1R3, 22.2R1-S1, or 22.2R2+). Schedule maintenance windows and test thoroughly in a lab environment before production deployment.

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= 21.1= 21.2= 21.3= 21.4= 22.1= 22.2

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
High

CVSS:3.1/AV:N/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 device model
    Run 'show chassis hardware' or 'show system information' to confirm the device is a Juniper MX Series router
    Affected if Device is not an MX Series router - this vulnerability only affects MX Series routers
  2. Check Junos OS version
    Run 'show version' to obtain the installed Junos OS version
    Affected if Version matches any of these: < 20.4, 20.4, 21.1, 21.2, 21.3, 21.4, 22.1, or 22.2 (not fixed versions)
  3. Verify PTP configuration
    Run 'show configuration protocol ptp' or 'show configuration | match ptp' to check if Precision Time Protocol is configured
    Affected if PTP is configured - the vulnerability is triggered specifically when PTP is enabled
  4. Check for FPC crash history
    Run 'show system core-dumps' or 'show log messages' for recent FPC (Flexible PIC Concentrator) crashes or restarts
    Affected if Recent FPC crashes or restarts occur without other known cause

A user is affected if they are running an MX Series router with an affected Junos version (20.4 through 22.2) and have PTP configured, which allows an attacker to trigger FPC crashes via routing protocol churn.

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 or later
Fixed in 20.4
Interim mitigation

Upgrade Junos OS to a fixed version (20.4R3-S4, 21.1R1+, 21.2R3-S2, 21.3R3-S5, 21.4R3, 22.1R3, 22.2R1-S1, or 22.2R2+). Schedule maintenance windows and test thoroughly in a lab environment before production deployment.

Recommended fix High confidence

Upgrade to 20.4R3-S4 or later, or 21.1R3 or later, or 21.2R3-S2 or later, or 21.3R3-S5 or later, or 21.4R3 or later, or 22.1R3 or later, or 22.2R2 or later (latest stable release recommended)

  1. 1. Verify current Junos OS version on the MX Series device using 'show version'
  2. 2. Confirm PTP (Precision Time Protocol) is configured using 'show configuration protocols ptp'
  3. 3. Identify the appropriate fixed version based on current running version: for 20.4.x upgrade to 20.4R3-S4 or later; for 21.1.x upgrade to 21.1R3 or later; for 21.2.x upgrade to 21.2R3-S2 or later; for 21.3.x upgrade to 21.3R3-S5 or later; for 21.4.x upgrade to 21.4R3 or later; for 22.1.x upgrade to 22.1R3 or later; for 22.2.x upgrade to 22.2R2 or later
  4. 4. Download the validated Junos OS upgrade image from Juniper Networks support portal
  5. 5. Back up current configuration using 'request system configuration backup'
  6. 6. Upload the upgrade image to the device using 'request system software add <package> no-validate'
  7. 7. Reboot the device using 'request system reboot'
  8. 8. After reboot, verify the new Junos version with 'show version' and confirm the FPC is stable with 'show chassis fpc'
Caveat Standard Junos upgrade precautions apply - review release notes for migration considerations and ensure configuration compatibility 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
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
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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-2023-44199 in production — separate from our analysis above.

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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
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  • No spam, self-promotion, credentials, or personal data