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Junos Os EvolvedOperating system · Juniper

CVE-2024-39559

MEDIUM · 5.9 CVSS v3.1 Published 2024-07-10
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
68/100
Remediation priority · Elevated
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 packet processing of Juniper Networks Junos OS Evolved may allow a network-based unauthenticated attacker to crash the device (vmcore) by sending a specific TCP packet over an established TCP session with MD5 authentication enabled, destined to an accessible port on the device, resulting in a Denial of Service (DoS).  The receipt of this packet must occur within a specific timing window outside the attacker's control (i.e., race condition). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue only affects dual RE systems with Nonstop Active Routing (NSR) enabled. Exploitation can only occur over TCP sessions with MD5 authentication enabled (e.g., BGP with MD5 authentication). This issue affects Junos OS Evolved:  * All versions before 21.2R3-S8-EVO, * from 21.4-EVO before 21.4R3-S6-EVO, * from 22.1-EVO before 22.1R3-S4-EVO, * from 22.2-EVO before 22.2R3-S4-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R2-S2-EVO, 22.4R3-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

A race condition in Junos OS Evolved's packet processing allows an unauthenticated attacker to crash dual RE systems with NSR enabled by sending a specially crafted TCP packet over an MD5-authenticated session (e.g., BGP with MD5). The vulnerability stems from an improper check for unusual conditions during a specific timing window, causing a vmcore crash and sustained DoS.

MitigationUpgrade Junos OS Evolved to the fixed versions (21.2R3-S8-EVO, 21.4R3-S6-EVO, 22.1R3-S4-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R2-S2-EVO or later). Until patched, monitor for unexpected device crashes and consider disabling MD5 authentication if operationally feasible.

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
Junos Os EvolvedOperating system
Affected:< 21.2= 21.2= 21.4= 22.1= 22.2= 22.3= 22.4

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
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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 Junos OS Evolved is running
    Identify the device OS and version using system information commands
    Affected if The device runs any version of Junos OS Evolved within the affected range (< 21.2, 21.2, 21.4, 22.1, 22.2, 22.3, or 22.4)
  2. Verify dual Routing Engine hardware
    Check whether the system has two Routing Engines installed
    Affected if The system has dual RE hardware present
  3. Confirm NSR is enabled
    Inspect the Non-Stop Routing configuration status
    Affected if NSR is enabled on the device
  4. Identify MD5-authenticated TCP sessions
    Look for configured MD5 authentication on TCP-based protocols (such as BGP with MD5)
    Affected if Any MD5-authenticated sessions (e.g., BGP with MD5) are configured and active

A system is affected if it runs Junos OS Evolved in the affected version range, has dual RE hardware with NSR enabled, and has MD5-authenticated TCP sessions configured.

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 21.2 or later
Fixed in 21.2
Interim mitigation

Upgrade Junos OS Evolved to the fixed versions (21.2R3-S8-EVO, 21.4R3-S6-EVO, 22.1R3-S4-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R2-S2-EVO or later). Until patched, monitor for unexpected device crashes and consider disabling MD5 authentication if operationally feasible.

Recommended fix High confidence

Upgrade to 21.2R3-S8-EVO, 21.4R3-S6-EVO, 22.1R3-S4-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, or 22.4R2-S2-EVO (or later) based on your current release branch

  1. 1. Identify the current Junos OS Evolved version running on the device using 'show version'
  2. 2. Verify if the device is a dual RE system with NSR enabled using 'show chassis redundancy'
  3. 3. Identify any TCP sessions with MD5 authentication (e.g., BGP with MD5) using 'show bgp neighbor'
  4. 4. Plan an upgrade to the appropriate fixed version based on current release branch
  5. 5. Schedule a maintenance window as upgrade will require device reboot
  6. 6. Download the appropriate upgrade image from Juniper support portal (e.g., 21.2R3-S8-EVO, 21.4R3-S6-EVO, 22.1R3-S4-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, or 22.4R2-S2-EVO)
  7. 7. Upload the software package to the device using 'file copy' or USB
  8. 8. Install the upgrade using 'request system software add <package> reboot'
Caveat Standard Junos OS upgrade - ensure compatibility with existing configuration and review release notes for any behavioral changes; NSR may have specific upgrade considerations

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

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2024-39559 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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