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JunosOperating system · Juniper

CVE-2023-44191

HIGH · 7.5 CVSS v3.1 Published 2023-10-13
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 Allocation of Resources Without Limits or Throttling vulnerability in Juniper Networks Junos OS allows an unauthenticated, network-based attacker to cause Denial of Service (DoS). On all Junos OS QFX5000 Series and EX4000 Series platforms, when a high number of VLANs are configured, a specific DHCP packet will cause PFE hogging which will lead to dropping of socket connections. This issue affects: Juniper Networks Junos OS on QFX5000 Series and EX4000 Series * 21.1 versions prior to 21.1R3-S5; * 21.2 versions prior to 21.2R3-S5; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S4; * 22.1 versions prior to 22.1R3-S3; * 22.2 versions prior to 22.2R3-S1; * 22.3 versions prior to 22.3R2-S2, 22.3R3; * 22.4 versions prior to 22.4R2. This issue does not affect Juniper Networks Junos OS versions prior to 21.1R1

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

An unauthenticated network attacker can send a specific DHCP packet to QFX5000 Series and EX4000 Series switches with many VLANs configured, causing Packet Forwarding Engine (PFE) resource exhaustion (hogging). This leads to socket connection drops and complete Denial of Service.

MitigationUpgrade Junos OS to a fixed version (21.1R3-S5, 21.2R3-S5, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R2-S2/22.3R3, or 22.4R2 or later) or apply available vendor patches.

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:= 21.1= 21.2= 21.3= 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
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. Identify device model
    Run 'show chassis hardware' or check the physical device label to confirm it is a QFX5000 Series or EX4000 Series switch
    Affected if Device is NOT a QFX5000 or EX4000 series switch (other models are not affected by this CVE)
  2. Check Junos OS version
    Run 'show version' or 'show version detail' to retrieve the installed Junos OS version
    Affected if Version matches 21.1, 21.2, 21.3, 21.4, 22.1, 22.2, 22.3, or 22.4 (any of the listed affected versions)
  3. Count configured VLANs
    Run 'show vlans | count' or 'show configuration vlans | count' to determine the number of VLANs configured on the device
    Affected if Many VLANs are configured (the vulnerability triggers when a specific DHCP packet is processed with numerous VLANs present)
  4. Verify DHCP service is accessible
    Run 'show services dhcp summary' or check 'show configuration forwarding-options helpers' to see if DHCP relay/helper is enabled
    Affected if DHCP is enabled or the switch is directly accessible to unauthenticated network attackers on VLANs with DHCP traffic

A user is affected if the device is a QFX5000 or EX4000 series switch running Junos 21.1-22.4 with many VLANs configured and DHCP traffic is present on the network.

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

Upgrade Junos OS to a fixed version (21.1R3-S5, 21.2R3-S5, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R2-S2/22.3R3, or 22.4R2 or later) or apply available vendor patches.

Recommended fix High confidence

Upgrade to 21.1R3-S5 or later (21.1 branch), 21.2R3-S5 or later (21.2 branch), 21.3R3-S5 or later (21.3 branch), 21.4R3-S4 or later (21.4 branch), or any 22.x version beyond the fixed releases listed above

  1. 1. Identify the current Junos OS version on the QFX5000 Series or EX4000 Series device using 'show version'
  2. 2. Determine if the current version is affected (21.1 before 21.1R3-S5, 21.2 before 21.2R3-S5, 21.3 before 21.3R3-S5, 21.4 before 21.4R3-S4, 22.1 before 22.1R3-S3, 22.2 before 22.2R3-S1, 22.3 before 22.3R2-S2/22.3R3, or 22.4 before 22.4R2)
  3. 3. Plan maintenance window as upgrade requires system reboot
  4. 4. Download the appropriate fixed Junos OS version from Juniper support portal (supportportal.juniper.net)
  5. 5. Upload the upgrade image to the device using 'request system software add <package>' or via USB
  6. 6. Reboot the device using 'request system reboot'
  7. 7. After reboot, verify the new version is running with 'show version'
  8. 8. Verify DHCP relay/relay functionality is working and no PFE hogging occurs
Caveat Standard Junos OS upgrade may cause brief service interruption; ensure configuration backup before upgrade; some legacy features may be deprecated in newer branches

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

Fix this in Junos Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2023-44191 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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