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JunosOperating system · Juniper

CVE-2024-39530

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 Improper Check for Unusual or Exceptional Conditions vulnerability in the chassis management daemon (chassisd) of Juniper Networks Junos OS allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an attempt is made to access specific sensors on platforms not supporting these sensors, either via GRPC or netconf, chassisd will crash and restart leading to a restart of all FPCs and thereby a complete outage. This issue affects Junos OS: * 21.4 versions from 21.4R3 before 21.4R3-S5, * 22.1 versions from 22.1R3 before 22.1R3-S4, * 22.2 versions from 22.2R2 before 22.2R3, * 22.3 versions from 22.3R1 before 22.3R2-S2, 22.3R3, * 22.4 versions from 22.4R1 before 22.4R2. This issue does not affect Junos OS versions earlier than 21.4.

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 Junos OS chassis management daemon (chassisd) allows unauthenticated attackers to cause denial of service by requesting specific sensors on platforms that do not support those sensors via GRPC or netconf. The daemon fails to handle this exceptional condition properly, crashes, and triggers a restart of all FPCs, causing complete network outage.

MitigationApply the vendor-supplied patches: upgrade to 21.4R3-S5, 22.1R3-S4, 22.2R3, 22.3R2-S2/22.3R3, or 22.4R2 or later. Restrict netconf/GRPC access to trusted networks as an interim measure.

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= 21.1= 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
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. Check Junos OS version
    Run 'show version' or 'show version detail' on the device CLI and note the firmware version (e.g., 21.4R1, 22.2R1, etc.)
    Affected if The installed version is 21.1, 21.4, 22.2, 22.3, or 22.4 (any release before the fixed versions: 21.4R3-S5, 22.1R3-S4, 22.2R3, 22.3R2-S2/22.3R3, or 22.4R2)
  2. Verify netconf service is enabled
    Run 'show configuration services netconf' to see if netconf is configured
    Affected if netconf is enabled and accessible from untrusted networks (the vulnerability is exploitable via netconf)
  3. Verify GRPC service is enabled
    Run 'show configuration system services grpc' to check if gRPC is configured
    Affected if gRPC service is enabled and accessible from untrusted networks (the vulnerability is exploitable via gRPC)
  4. Check for prior chassisd crashes
    Run 'show system core-dumps' and review system logs (show log messages) for chassisd crash events or FPC restart messages
    Affected if Recent chassisd crashes or unexplained FPC restarts have occurred and correlate with external netconf/gRPC requests

You are likely affected if your Junos version is in the 21.1/21.4/22.2/22.3/22.4 family and netconf or gRPC services are exposed to untrusted networks, as an unauthenticated attacker could trigger the chassisd crash and FPC restart.

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 vendor-supplied patches: upgrade to 21.4R3-S5, 22.1R3-S4, 22.2R3, 22.3R2-S2/22.3R3, or 22.4R2 or later. Restrict netconf/GRPC access to trusted networks as an interim measure.

Recommended fix High confidence

21.4R3-S5, 22.1R3-S4, 22.2R3, 22.3R2-S2, 22.3R3, or 22.4R2 (depending on your current branch)

  1. 1. Identify current Junos OS version by running 'show version' command
  2. 2. Based on current version, plan upgrade to the minimum fixed release: For 21.4R3.x - upgrade to 21.4R3-S5 or later; For 22.1R3.x - upgrade to 22.1R3-S4 or later; For 22.2R2.x - upgrade to 22.2R3 or later; For 22.3R1-R2 - upgrade to 22.3R2-S2 or later; For 22.3R3 - already fixed; For 22.4R1 - upgrade to 22.4R2 or later
  3. 3. Before upgrade, backup configuration using 'request system configuration rescue save'
  4. 4. Download the appropriate Junos upgrade image from Juniper support portal
  5. 5. Perform upgrade via 'request system software add <package> no-validate reboot'
  6. 6. After reboot, verify chassisd is running with 'show chassis management' and confirm FPCs are online with 'show chassis fpc'
  7. 7. Verify the new version is running with 'show version'
Caveat Standard Junos upgrade precautions apply - ensure configuration compatibility and have console access in case of boot issues

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
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2024-39530 in production — separate from our analysis above.

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