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Junos Os EvolvedOperating system · Juniper

CVE-2024-39526

MEDIUM · 6.5 CVSS v3.1 Published 2024-10-11
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
70/100
Remediation priority · Elevated
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 Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C lines cards, MX304 devices, and Juniper Networks Junos OS Evolved on PTX Series, allows an attacker sending malformed DHCP packets to cause ingress packet processing to stop, leading to a Denial of Service (DoS).  Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. This issue only occurs if DHCP snooping is enabled. See configuration below. This issue can be detected using following commands. Their output will display the interface status going down: user@device>show interfaces <if--x/x/x> user@device>show log messages | match <if--x/x/x> user@device>show log messages ==> will display the "[Error] Wedge-Detect : Host Loopback Wedge Detected: PFE: no," logs. This issue affects: Junos OS on MX Series with MPC10/MPC11/LC9600 line cards, EX9200 with EX9200-15C line cards, and MX304: * All versions before 21.2R3-S7, * from 21.4 before 21.4R3-S6, * from 22.2 before 22.2R3-S3, * all versions of 22.3, * from 22.4 before 22.4R3, * from 23.2 before 23.2R2; Junos OS Evolved on PTX Series: * from 19.3R1-EVO before 21.2R3-S8-EVO, * from 21.4-EVO before 21.4R3-S7-EVO, * from 22.1-EVO before 22.1R3-S6-EVO, * from 22.2-EVO before 22.2R3-S5-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R3-S1-EVO, * from 23.2-EVO before 23.2R2-S2-EVO, * from 23.4-EVO before 23.4R2-EVO. Junos OS Evolved releases prior to 19.3R1-EVO are unaffected by this vulnerability

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 software defect in Junos OS packet processing causes a host loopback wedge when malformed DHCP packets are received on devices with DHCP snooping enabled. This wedge condition halts all ingress packet processing on affected line cards, resulting in a sustained DoS until the packets cease or the device is rebooted.

MitigationApply the vendor-supplied software patches/updates to reach a fixed version (21.2R3-S7, 21.4R3-S6, 22.2R3-S3, 22.4R3, 23.2R2 or later for Junos OS; 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.1R3-S6-EVO, 22.2R3-S5-EVO, 22.3R3-S3-EVO, 22.4R3-S1-EVO, 23.2R2-S2-EVO, 23.4R2-EVO or later for Junos OS Evolved). As a temporary workaround, disable DHCP snooping 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:>= 19.4, < 21.2= 19.3= 21.2= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2= 23.4
JunosOperating system
Affected:< 21.2= 21.2= 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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/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. Determine Junos OS version
    Run 'show version' or 'show version detail' to obtain the installed Junos version
    Affected if The version matches any of the affected ranges: Junos OS Evolved: 19.3, 19.4 through <21.2, 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, 23.2, 23.4; Junos: <21.2, 21.2, 21.4, 22.2, 22.3, 22.4, 23.2
  2. Verify DHCP snooping is enabled
    Run 'show configuration | display set | match dhcp-snooping' or 'show dhcp snooping' to check if DHCP snooping is configured
    Affected if DHCP snooping is enabled (the vulnerability only affects devices with DHCP snooping turned on)
  3. Inspect for wedge condition symptoms
    Run 'show chassis fabric fpc' or 'show interfaces' to check for stalled packet processing; look for unexpected traffic interruption on line cards
    Affected if Ingress packet processing is halted on line cards and traffic has stopped without manual intervention or device reboot

You are affected if your device runs a vulnerable Junos version AND has DHCP snooping enabled, and you are experiencing a sustained packet processing halt on line cards after receiving malformed DHCP 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 21.2 or later
Fixed in 21.2
Interim mitigation

Apply the vendor-supplied software patches/updates to reach a fixed version (21.2R3-S7, 21.4R3-S6, 22.2R3-S3, 22.4R3, 23.2R2 or later for Junos OS; 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.1R3-S6-EVO, 22.2R3-S5-EVO, 22.3R3-S3-EVO, 22.4R3-S1-EVO, 23.2R2-S2-EVO, 23.4R2-EVO or later for Junos OS Evolved). As a temporary workaround, disable DHCP snooping if operationally feasible.

Recommended fix High confidence

Upgrade to Junos OS 21.2R3-S7/21.4R3-S6/22.2R3-S3/22.4R3/23.2R2 or later, or Junos OS Evolved 21.2R3-S8-EVO/21.4R3-S7-EVO/22.1R3-S6-EVO/22.2R3-S5-EVO/22.3R3-S3-EVO/22.4R3-S1-EVO/23.2R2-S2-EVO/23.4R2-EVO

  1. 1. Identify the current Junos OS/Junos OS Evolved version on the device using 'show version'
  2. 2. Identify the hardware platform (MX Series with MPC10/MPC11/LC9600, EX9200 with EX9200-15C, MX304, or PTX Series for Evolved)
  3. 3. Identify whether DHCP snooping is enabled using 'show configuration | match dhcp-snooping'
  4. 4. If DHCP snooping is not required as a temporary mitigation, disable it with 'delete forwarding-options dhcp-snooping' and commit
  5. 5. Upgrade to a fixed version based on your current branch: For 21.2 branch, upgrade to 21.2R3-S7 or later; For 21.4 branch, upgrade to 21.4R3-S6 or later; For 22.2 branch, upgrade to 22.2R3-S3 or later; For 22.3 branch, upgrade to any 22.3R3-Sx or later; For 22.4 branch, upgrade to 22.4R3 or later; For 23.2 branch, upgrade to 23.2R2 or later
  6. 6. For Junos OS Evolved on PTX Series: Upgrade to 21.2R3-S8-EVO, 21.4R3-S7-EVO, 22.1R3-S6-EVO, 22.2R3-S5-EVO, 22.3R3-S3-EVO, 22.4R3-S1-EVO, 23.2R2-S2-EVO, or 23.4R2-EVO respectively
  7. 7. After upgrade, verify the fix using 'show version' and confirm interfaces remain operational
  8. 8. Monitor logs with 'show log messages | match wedge' to confirm the issue is resolved
Caveat Review Juniper release notes for any compatibility notes or migration considerations before upgrading; S-Space releases are maintenance releases with minimal risk

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
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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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-2024-39526 in production — separate from our analysis above.

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What belongs here
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