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JunosOperating system · Juniper

CVE-2024-39556

HIGH · 7.0 CVSS v3.1 Published 2024-07-10
Fix available
A fix is available. Upgrade to 21.4 or later.
See remediation →
72/100
Remediation priority · Elevated
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 Stack-Based Buffer Overflow vulnerability in Juniper Networks Junos OS and Juniper Networks Junos OS Evolved may allow a local, low-privileged attacker with access to the CLI the ability to load a malicious certificate file, leading to a limited Denial of Service (DoS) or privileged code execution. By exploiting the 'set security certificates' command with a crafted certificate file, a malicious attacker with access to the CLI could cause a crash of the command management daemon (mgd), limited to the local user's command interpreter, or potentially trigger a stack-based buffer overflow. This issue affects:  Junos OS: * All versions before 21.4R3-S7, * from 22.1 before 22.1R3-S6, * from 22.2 before 22.2R3-S4, * from 22.3 before 22.3R3-S3, * from 22.4 before 22.4R3-S2, * from 23.2 before 23.2R2, * from 23.4 before 23.4R1-S1, 23.4R2;  Junos OS Evolved: * All versions before 21.4R3-S7-EVO, * from 22.1-EVO before 22.1R3-S6-EVO, * from 22.2-EVO before 22.2R3-S4-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R3-S2-EVO, * from 23.2-EVO before 23.2R2-EVO, * from 23.4-EVO before 23.4R1-S1-EVO, 23.4R2-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

Stack-based buffer overflow in Juniper Junos OS CLI certificate handling allows local low-privileged attacker with CLI access to load malicious certificate file via 'set security certificates' command, causing mgd daemon crash (DoS) or potentially achieving privileged code execution.

MitigationApply vendor-provided patches/updates to the specific versions listed in the advisory; restrict CLI access to trusted personnel and monitor for unauthorized certificate loading attempts.

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= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2= 23.4
Junos Os EvolvedOperating system
Affected:< 21.4= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2= 23.4

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
Local
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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 Junos OS version
    Run 'show version' or 'show version detail' via CLI to obtain the installed Junos version
    Affected if Version matches < 21.4; = 21.4; = 22.1; = 22.2; = 22.3; = 22.4; = 23.2; or = 23.4
  2. Verify if CLI access is available to untrusted users
    Review user account configurations and login access permissions using 'show system login' and 'show configuration system login'
    Affected if Low-privileged or untrusted users have CLI access
  3. Inspect loaded certificates
    Run 'show security certificates' to list all certificates loaded via the 'set security certificates' command
    Affected if Unknown or suspicious certificates are present that were not loaded by authorized administrators
  4. Check for mgd daemon crashes
    Review system logs with 'show log messages' and look for mgd daemon restart events or crash indicators
    Affected if Recent mgd daemon crashes or restarts occurred without known cause
  5. Audit recent certificate import commands
    Run 'show system audit' or review system logs for recent 'set security certificates' command executions
    Affected if Certificate loading commands were executed by unexpected users or at unusual times

A system is affected if it runs a vulnerable Junos version AND has CLI access available to untrusted users, with the vulnerability triggerable via the 'set security certificates' command.

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 21.4 or later
Fixed in 21.4
Interim mitigation

Apply vendor-provided patches/updates to the specific versions listed in the advisory; restrict CLI access to trusted personnel and monitor for unauthorized certificate loading attempts.

Recommended fix High confidence

Upgrade to 21.4R3-S7 / 22.1R3-S6 / 22.2R3-S4 / 22.3R3-S3 / 22.4R3-S2 / 23.2R2 / 23.4R2 (or later) for Junos OS; or corresponding -EVO versions for Junos OS Evolved

  1. 1. Identify the current Junos OS or Junos OS Evolved version running on the device using 'show version' command.
  2. 2. Determine the appropriate upgrade path based on the current version branch (21.4, 22.1, 22.2, 22.3, 22.4, 23.2, or 23.4).
  3. 3. For Junos OS: upgrade to the fixed version for your branch: 21.4R3-S7, 22.1R3-S6, 22.2R3-S4, 22.3R3-S3, 22.4R3-S2, 23.2R2, or 23.4R2 (or 23.4R1-S1).
  4. 4. For Junos OS Evolved: upgrade to the fixed version for your branch: 21.4R3-S7-EVO, 22.1R3-S6-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S2-EVO, 23.2R2-EVO, or 23.4R2-EVO (or 23.4R1-S1-EVO).
  5. 5. Download the appropriate upgrade image from the Juniper Networks support portal (supportportal.juniper.net).
  6. 6. Upload the upgrade image to the device using 'request system software add' command with the validate option first.
  7. 7. Reboot the device after successful upgrade using 'request system reboot'.
  8. 8. After reboot, verify the new version is running with 'show version' and confirm the vulnerability is resolved.
Caveat Standard Junos upgrade considerations apply - review release notes for your target version for any compatibility notices or configuration changes

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-2024-39556 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
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  • Version or environment caveats, and links to real fixes
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