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JunosOperating system · Juniper

CVE-2024-39551

HIGH · 7.5 CVSS v3.1 Published 2024-07-11
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 Uncontrolled Resource Consumption vulnerability in the H.323 ALG (Application Layer Gateway) of  Juniper Networks Junos OS on SRX Series and MX Series with SPC3 and MS-MPC/MIC, allows an unauthenticated network-based attacker to send specific packets causing traffic loss leading to Denial of Service (DoS).  Continued receipt and processing of these specific packets will sustain the Denial of Service condition. The memory usage can be monitored using the below command.   user@host> show usp memory segment sha data objcache jsf  This issue affects SRX Series and MX Series with SPC3 and MS-MPC/MIC:  *  20.4 before 20.4R3-S10,  *  21.2 before 21.2R3-S6,  *  21.3 before 21.3R3-S5,  *  21.4 before 21.4R3-S6,  *  22.1 before 22.1R3-S4,  *  22.2 before 22.2R3-S2,  *  22.3 before 22.3R3-S1,  *  22.4 before 22.4R3,  *  23.2 before 23.2R2.

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

An Uncontrolled Resource Consumption vulnerability in the H.323 ALG (Application Layer Gateway) of Juniper Networks Junos OS on SRX Series and MX Series with SPC3 and MS-MPC/MIC allows an unauthenticated network-based attacker to send specific H.323 packets causing excessive memory consumption, leading to traffic loss and sustained Denial of Service condition.

MitigationApply the appropriate Junos OS software update (20.4R3-S10, 21.2R3-S6, 21.3R3-S5, 21.4R3-S6, 22.1R3-S4, 22.2R3-S2, 22.3R3-S1, 22.4R3, or 23.2R2 or later per branch). Until patched, consider filtering or blocking H.323 traffic at network perimeter as a compensating control.

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= 23.2

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 the device model
    Run 'show chassis hardware' or check the physical device to confirm it is an SRX Series firewall or MX Series router with SPC3, MS-MPC, or MS-MIC line cards installed.
    Affected if Device is not an SRX Series or MX Series with SPC3/MS-MPC/MS-MIC, then it is not affected.
  2. Determine the Junos OS version
    Run 'show version' or 'show version detail' to obtain the installed Junos OS version.
    Affected if Version matches 20.4R1-R3, 21.2R1-R3, 21.3R1-R3, 21.4R1-R3, 22.1R1-R3, 22.2R1-R3, 22.3R1, 22.4R1-R3, or 23.2R1 (prior to the fixed versions per branch). Compare against the affected version list provided.
  3. Verify H.323 ALG is enabled
    Run 'show security alg h323' to check the H.323 ALG status. Also run 'show security alg' to list all active ALGs.
    Affected if H.323 ALG is enabled and active on the device, creating the attack surface for this vulnerability.
  4. Check for H.323 traffic patterns
    Monitor firewall logs and session tables using 'show security flow session protocol h323' and review system logs for abnormal H.323 traffic or memory consumption patterns.
    Affected if H.323 traffic is being processed by the device, indicating potential exposure to the vulnerability.

A user is affected if they are running a vulnerable Junos OS version on an SRX or MX Series device with SPC3/MS-MPC/MS-MIC, and the H.323 ALG is enabled and processing H.323 traffic.

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 the appropriate Junos OS software update (20.4R3-S10, 21.2R3-S6, 21.3R3-S5, 21.4R3-S6, 22.1R3-S4, 22.2R3-S2, 22.3R3-S1, 22.4R3, or 23.2R2 or later per branch). Until patched, consider filtering or blocking H.323 traffic at network perimeter as a compensating control.

Recommended fix High confidence

Upgrade to 20.4R3-S10, 21.2R3-S6, 21.3R3-S5, 21.4R3-S6, 22.1R3-S4, 22.2R3-S2, 22.3R3-S1, 22.4R3, or 23.2R2 (or later) depending on your current branch. Recommend upgrading to the latest stable release in your branch or moving to a supported release like 22.4 or 23.2.

  1. 1. Identify the current Junos OS version running on the affected SRX Series or MX Series device using: `show version`
  2. 2. Determine if H.323 ALG is enabled using: `show security alg h323`
  3. 3. Plan the upgrade to a fixed version based on your current branch: For 20.4.x upgrade to 20.4R3-S10 or later; For 21.2.x upgrade to 21.2R3-S6 or later; For 21.3.x upgrade to 21.3R3-S5 or later; For 21.4.x upgrade to 21.4R3-S6 or later
  4. 4. Schedule a maintenance window as upgrades require device reboot
  5. 5. Download the appropriate Junos OS upgrade image from Juniper Networks support portal
  6. 6. Upload the upgrade image to the device using: `file copy` or USB
  7. 7. Validate the image integrity using: `request system software validate <image>`
  8. 8. Execute the upgrade using: `request system software add <image> reboot`
Caveat Upgrades may cause brief service disruption as the device reboots; ensure compatibility with other installed modules (SPC3, MS-MPC/MIC) and review Junos OS upgrade guidelines for your specific hardware platform.

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

Fix this in Junos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
18.0 hours of engineering $3,040
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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-2024-39551 in production — separate from our analysis above.

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