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JunosOperating system · Juniper

CVE-2023-0026

HIGH · 7.5 CVSS v3.1 Published 2023-06-21
Fix available
A fix is available. Upgrade to 20.4 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
An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS). When a BGP update message is received over an established BGP session, and that message contains a specific, optional transitive attribute, this session will be torn down with an update message error. This issue cannot propagate beyond an affected system as the processing error occurs as soon as the update is received. This issue is exploitable remotely as the respective attribute can propagate through unaffected systems and intermediate AS (if any). Continuous receipt of a BGP update containing this attribute will create a sustained Denial of Service (DoS) condition. Some customers have experienced these BGP session flaps which prompted Juniper SIRT to release this advisory out of cycle before fixed releases are widely available as there is an effective workaround. This issue affects: Juniper Networks Junos OS 15.1R1 and later versions prior to 20.4R3-S8; 21.1 version 21.1R1 and later versions prior to 21.2R3-S6; 21.3 versions prior to 21.3R3-S5; 21.4 versions prior to 21.4R3-S4; 22.1 versions prior to 22.1R3-S4; 22.2 versions prior to 22.2R3-S2; 22.3 versions prior to 22.3R2-S2, 22.3R3-S1; 22.4 versions prior to 22.4R2-S1, 22.4R3; 23.1 versions prior to 23.1R1-S1, 23.1R2. Juniper Networks Junos OS Evolved All versions prior to 20.4R3-S8-EVO; 21.1 version 21.1R1-EVO and later versions prior to 21.2R3-S6-EVO; 21.3 versions prior to 21.3R3-S5-EVO; 21.4 versions prior to 21.4R3-S4-EVO; 22.1 versions prior to 22.1R3-S4-EVO; 22.2 versions prior to 22.2R3-S2-EVO; 22.3 versions prior to 22.3R2-S2-EVO, 22.3R3-S1-EVO; 22.4 versions prior to 22.4R2-S1-EVO, 22.4R3-EVO; 23.1 versions prior to 23.1R1-S1-EVO, 23.1R2-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

Improper input validation in Juniper rpd allows unauthenticated remote attackers to cause DoS by sending BGP updates containing a specific optional transitive attribute, causing session teardown. Continuous exploitation creates sustained DoS.

MitigationApply Junos OS/Evolved vendor patches (20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S1/22.4R3, 23.1R1-S1/23.1R2) per Juniper's advisory. An effective workaround exists and should be implemented pending upgrade.

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:>= 15.1, < 20.4= 20.4= 21.1= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4
Junos Os EvolvedOperating system
Affected:< 20.4= 20.4= 21.1= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4= 23.1

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 the Junos version
    Run 'show version' or 'request system version' on the device CLI
    Affected if The version matches any of: 15.1 through 19.x, 20.4, 21.1, 21.2, 21.3, 21.4, 22.1, 22.2, 22.3, 22.4, or 23.1 (for Junos OS Evolved)
  2. Confirm BGP is configured
    Run 'show configuration protocols bgp' to see if BGP protocol is enabled
    Affected if BGP protocol is configured and active on the device (the vulnerability is only exploitable via BGP)
  3. Check for BGP session instability
    Run 'show bgp summary' repeatedly or review logs for unexpected BGP peer state changes
    Affected if BGP sessions are frequently dropping or showing 'Active' state without recovery, which may indicate exploitation attempts

If the device runs an affected Junos version AND has BGP configured, it is vulnerable to this DoS flaw via specially crafted BGP updates.

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 20.4 or later
Fixed in 20.4
Interim mitigation

Apply Junos OS/Evolved vendor patches (20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S1/22.4R3, 23.1R1-S1/23.1R2) per Juniper's advisory. An effective workaround exists and should be implemented pending upgrade.

Recommended fix High confidence

Upgrade to Junos OS 20.4R3-S8 / 21.2R3-S6 / 21.3R3-S5 / 21.4R3-S4 / 22.1R3-S4 / 22.2R3-S2 / 22.3R3-S1 / 22.4R3 / 23.1R2 or later; or Junos OS Evolved 20.4R3-S8-EVO / 21.2R3-S6-EVO / 21.3R3-S5-EVO / 21.4R3-S4-EVO / 22.1R3-S4-EVO / 22.2R3-S2-EVO / 22.3R3-S1-EVO / 22.4R3-EVO / 23.1R2-EVO or later

  1. 1. Identify the exact Junos OS or Junos OS Evolved version currently running on the affected device using 'show version' command.
  2. 2. Based on the version identified, upgrade to one of the fixed releases: 20.4R3-S8 or later for the 20.4 branch, 21.2R3-S6 or later for the 21.2 branch, 21.3R3-S5 or later for the 21.3 branch, 21.4R3-S4 or later for the 21.4 branch, 22.1R3-S4 or later for the 22.1 branch, 22.2R3-S2 or later for the 22.2 branch, 22.3R3-S1 or later for the 22.3 branch, 22.4R3 or later for the 22.4 branch, or 23.1R2
  3. 3. Download the appropriate Junos upgrade package from the Juniper Networks support portal (supportportal.juniper.net).
  4. 4. Upload the upgrade package to the device using 'file copy' or similar method, or configure the device to upgrade from a configured software repository.
  5. 5. Initiate the upgrade using the 'request system software add <package-name>' command for Junos OS, or follow the specific upgrade procedure for Junos OS Evolved.
  6. 6. After the upgrade completes, reboot the device using 'request system reboot' command.
  7. 7. After the device restarts, verify the new Junos version is installed using 'show version'.
  8. 8. Verify BGP sessions are operational using 'show bgp summary' and monitor for any session flaps.
Caveat Standard Junos upgrade risks apply - ensure compatibility with other network devices and review Junos upgrade guidelines; test in lab environment before production deployment

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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

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Peer-ranked notes from engineers who’ve handled CVE-2023-0026 in production — separate from our analysis above.

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What belongs here
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