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JunosOperating system · Juniper

CVE-2023-28976

HIGH · 7.5 CVSS v3.1 Published 2023-04-17
Fix available
A fix is available. Upgrade to 19.1 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 an unauthenticated, network-based attacker to cause a Denial of Service (DoS). If specific traffic is received on MX Series and its rate exceeds the respective DDoS protection limit the ingress PFE will crash and restart. Continued receipt of this traffic will create a sustained DoS condition. This issue affects Juniper Networks Junos OS on MX Series: All versions prior to 19.1R3-S10; 19.2 versions prior to 19.2R3-S7; 19.3 versions prior to 19.3R3-S8; 19.4 versions prior to 19.4R3-S11; 20.2 versions prior to 20.2R3-S5; 20.4 versions prior to 20.4R3-S6; 21.1 versions prior to 21.1R3-S5; 21.2 versions prior to 21.2R3-S4; 21.3 versions prior to 21.3R3; 21.4 versions prior to 21.4R3; 22.1 versions prior to 22.1R2.

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 Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to cause denial of service. When specific traffic exceeds the DDoS protection limit, the PFE fails to properly handle this exceptional condition, causing the ingress PFE to crash and restart, creating a sustained DoS condition.

MitigationApply the vendor-supplied software updates (patches) for Junos OS on MX Series devices to address the improper check for unusual conditions in the PFE.

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:< 19.1= 19.1= 19.2= 19.3= 19.4= 20.2= 20.4= 21.1= 21.2= 21.3= 21.4= 22.1

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. Confirm device is MX Series
    Run 'show chassis hardware' or 'show version' to identify the device model. Look for MX in the model name.
    Affected if Device is not an MX Series router - the vulnerability only affects MX Series devices
  2. Check Junos OS version
    Run 'show version' to display the installed Junos OS version. Compare against affected versions: < 19.1, 19.1, 19.2, 19.3, 19.4, 20.2, 20.4, 21.1, 21.2, 21.3, 21.4, 22.1
    Affected if Installed version matches one of the listed affected versions (note: versions 20.1, 20.3, 22.2+ may not be listed and could be patched)
  3. Verify PFE status and check for recent crashes
    Run 'show pfe statistics' and 'show chassis firmware' to check PFE health. Review system logs with 'show log messages' for PFE crash or restart events.
    Affected if PFE shows crash/restart events in logs or statistics indicate unexpected restarts
  4. Check for DDoS violation logs
    Run 'show ddos protection statistics' to examine DDoS packet violations. Look for bursts that may have triggered the vulnerability condition.
    Affected if DDoS statistics show unusual traffic patterns exceeding protection limits, or the PFE has restarted due to traffic anomalies

The device is affected if it is an MX Series router running a Junos OS version in the affected list and exhibits PFE crash/restart behavior or DDoS-related traffic anomalies.

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 19.1 or later
Fixed in 19.1
Interim mitigation

Apply the vendor-supplied software updates (patches) for Junos OS on MX Series devices to address the improper check for unusual conditions in the PFE.

Recommended fix High confidence

19.1R3-S10 / 19.2R3-S7 / 19.3R3-S8 / 19.4R3-S11 / 20.2R3-S5 / 20.4R3-S6 / 21.1R3-S5 / 21.2R3-S4 / 21.3R3 / 21.4R3 / 22.1R2 (or later)

  1. 1. Identify the current Junos OS version running on the MX Series device using 'show version'
  2. 2. Determine the appropriate upgrade path based on current version and compatibility requirements
  3. 3. Schedule a maintenance window as the upgrade will require a system reboot
  4. 4. Download the appropriate fixed Junos OS release from Juniper Networks (e.g., 19.1R3-S10, 19.2R3-S7, 19.3R3-S8, or a later version as listed in the advisory)
  5. 5. Upload the new Junos OS image to the device using 'request system software add' or through the web UI
  6. 6. Reboot the device to complete the installation using 'request system reboot'
  7. 7. After reboot, verify the new version is running with 'show version'
  8. 8. Confirm the vulnerability is fixed by checking 'show chassis firmware' and verifying PFE stability
Caveat Standard Junos upgrade considerations apply - review release notes for any configuration changes, ensure compatibility with other network devices, and test in lab environment before production deployment

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2023-28976 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