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JunosOperating system · Juniper

CVE-2024-39529

HIGH · 7.5 CVSS v3.1 Published 2024-07-11
Fix available
A fix is available. Upgrade to 21.4 or later.
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
A Use of Externally-Controlled Format String vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If DNS Domain Generation Algorithm (DGA) detection or tunnel detection, and DNS-filtering traceoptions are configured, and specific valid transit DNS traffic is received this causes a PFE crash and restart, leading to a Denial of Service. This issue affects Junos OS: * All versions before 21.4R3-S6, * 22.2 versions before 22.2R3-S3, * 22.3 versions before 22.3R3-S3, * 22.4 versions before 22.4R3, * 23.2 versions 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

A Use of Externally-Controlled Format String vulnerability exists in the Packet Forwarding Engine (PFE) of Juniper SRX Series firewalls. When DNS Domain Generation Algorithm (DGA) detection or tunnel detection, along with DNS-filtering traceoptions are configured, receiving specific valid transit DNS packets triggers the format string flaw, causing the PFE to crash and restart, resulting in denial of service.

MitigationUpgrade Junos OS to a patched version (21.4R3-S6, 22.2R3-S3, 22.3R3-S3, 22.4R3, 23.2R2 or later). As a temporary workaround, consider disabling DNS DGA detection, tunnel detection, or DNS-filtering traceoptions if not required for your deployment.

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= 22.2= 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. Check the Junos OS version
    Run `show version` on the SRX device and note the installed Junos version
    Affected if The version is < 21.4, 21.4, 22.2, 22.3, 22.4, or 23.2
  2. Verify if DNS DGA detection is configured
    Run `show configuration security dns-filter` or search for dga-detection in the configuration using `show configuration | match dga`
    Affected if DNS DGA detection is enabled in the DNS-filter configuration
  3. Verify if tunnel detection is configured
    Run `show configuration | match tunnel-detection` to check for tunnel detection settings
    Affected if Tunnel detection is enabled in the security configuration
  4. Verify if DNS-filtering traceoptions are enabled
    Run `show configuration security traceoptions` or search for dns-filter related traceoptions using `show configuration | match dns-filter | match traceoptions`
    Affected if DNS-filtering traceoptions are configured and enabled

The environment is affected if the Junos version matches one of the affected versions AND (DNS DGA detection OR tunnel detection) AND DNS-filtering traceoptions are both configured, allowing the format string vulnerability to trigger upon receiving specific transit DNS packets.

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

Upgrade Junos OS to a patched version (21.4R3-S6, 22.2R3-S3, 22.3R3-S3, 22.4R3, 23.2R2 or later). As a temporary workaround, consider disabling DNS DGA detection, tunnel detection, or DNS-filtering traceoptions if not required for your deployment.

Recommended fix High confidence

Upgrade to 21.4R3-S6 or later (or the equivalent fixed version for your branch: 22.2R3-S3, 22.3R3-S3, 22.4R3, or 23.2R2)

  1. 1. Identify the current Junos OS version on the SRX device using 'show version'
  2. 2. Determine the appropriate fixed version based on current branch: for 21.4.x upgrade to 21.4R3-S6 or later; for 22.2.x upgrade to 22.2R3-S3 or later; for 22.3.x upgrade to 22.3R3-S3 or later; for 22.4.x upgrade to 22.4R3 or later; for 23.2.x upgrade to 23.2R2 or later
  3. 3. Schedule a maintenance window as the upgrade will cause a brief PFE restart/DoS (this is expected)
  4. 4. Backup the current configuration using 'request system configuration archive' or manual config backup
  5. 5. Download the appropriate Junos upgrade image from Juniper support portal
  6. 6. Upload the upgrade image to the SRX device
  7. 7. Install the upgrade using 'request system software add <package> reboot'
  8. 8. After reboot, verify the new version is running with 'show version'
Caveat Standard Junos upgrade downtime expected; PFE will restart during upgrade process

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
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

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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-2024-39529 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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  • No spam, self-promotion, credentials, or personal data