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JunosOperating system · Juniper

CVE-2024-21595

HIGH · 7.5 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 →
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 Validation of Syntactic Correctness of Input vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS allows a network-based, unauthenticated attacker to cause a Denial of Service (DoS). If an attacker sends high rate of specific ICMP traffic to a device with VXLAN configured, this causes a deadlock of the PFE and results in the device becoming unresponsive. A manual restart will be required to recover the device. This issue only affects EX4100, EX4400, EX4600, QFX5000 Series devices. This issue affects: Juniper Networks Junos OS * 21.4R3 versions earlier than 21.4R3-S4; * 22.1R3 versions earlier than 22.1R3-S3; * 22.2R2 versions earlier than 22.2R3-S1; * 22.3 versions earlier than 22.3R2-S2, 22.3R3; * 22.4 versions earlier than 22.4R2; * 23.1 versions earlier than 23.1R2.

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

Improper validation of syntactic correctness of input in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS allows an unauthenticated network attacker to send high-rate specific ICMP traffic to devices with VXLAN configured, causing PFE deadlock and resulting in DoS. Manual restart required to recover.

MitigationUpgrade Junos OS to the fixed versions (21.4R3-S4 and later, 22.1R3-S3 and later, 22.2R3-S1 and later, 22.3R2-S2/22.3R3 and later, 22.4R2 and later, 23.1R2 and later) for affected EX4100, EX4400, EX4600, and QFX5000 Series devices.

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:= 21.4= 22.1= 22.2= 22.3= 22.4= 23.1

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. Identify the Junos OS version
    Run 'show version' or 'show version detail' on the device CLI
    Affected if The version shown is any of: 21.4, 22.1, 22.2, 22.3, 22.4, or 23.1 (any subversion within these releases)
  2. Verify VXLAN configuration
    Run 'show configuration protocols vxlan' or 'show configuration | match vxlan' to check if VXLAN is configured
    Affected if VXLAN protocol is actively configured on the device
  3. Confirm device model is in affected series
    Run 'show chassis hardware' or 'show system information' to identify the hardware model
    Affected if The device is an EX4100, EX4400, EX4600, or QFX5000 series switch
  4. Check for PFE deadlock symptoms
    Run 'show pfe statistics error' and 'show chassis fpc pic-status' to verify PFE responsiveness
    Affected if PFE shows errors or FPC/PIC status indicates offline or unreachable state after ICMP traffic

The device is affected if it runs any 21.4, 22.1, 22.2, 22.3, 22.4, or 23.1 Junos version, has VXLAN configured, is an EX4100/EX4400/EX4600/QFX5000 series, and has received high-rate ICMP traffic causing PFE deadlock.

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

Upgrade Junos OS to the fixed versions (21.4R3-S4 and later, 22.1R3-S3 and later, 22.2R3-S1 and later, 22.3R2-S2/22.3R3 and later, 22.4R2 and later, 23.1R2 and later) for affected EX4100, EX4400, EX4600, and QFX5000 Series devices.

Recommended fix High confidence

Upgrade to one of: 21.4R3-S4 or later, 22.1R3-S3 or later, 22.2R3-S1 or later, 22.3R2-S2/22.3R3 or later, 22.4R2 or later, or 23.1R2 or later - choose the nearest stable release for your branch

  1. 1. Identify the exact Junos OS version currently running on the affected device using 'show version'
  2. 2. Determine the appropriate upgrade path based on current version (21.4R3 → 21.4R3-S4+, 22.1R3 → 22.1R3-S3+, 22.2R2 → 22.2R3-S1+, 22.3 → 22.3R2-S2 or 22.3R3+, 22.4 → 22.4R2+, 23.1 → 23.1R2+)
  3. 3. Download the fixed Junos OS software package from the Juniper Networks support portal
  4. 4. Upload the software package to the device using 'file copy' or USB transfer
  5. 5. Install the software upgrade using 'request system software add <package-name> reboot'
  6. 6. After reboot, verify the new version is running with 'show version' and confirm the vulnerability is resolved
  7. 7. Verify VXLAN functionality is operating normally after upgrade
Caveat Standard Junos upgrade precautions apply: backup configuration, verify hardware compatibility, test in lab first if possible; no specific breaking changes mentioned for this fix

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
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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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-2024-21595 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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