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JunosOperating system · Juniper

CVE-2024-21585

MEDIUM · 5.9 CVSS v3.1 Published 2024-01-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
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 Handling of Exceptional Conditions vulnerability in BGP session processing of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker, using specific timing outside the attacker's control, to flap BGP sessions and cause the routing protocol daemon (rpd) process to crash and restart, leading to a Denial of Service (DoS) condition. Continued BGP session flapping will create a sustained Denial of Service (DoS) condition. This issue only affects routers configured with non-stop routing (NSR) enabled. Graceful Restart (GR) helper mode, enabled by default, is also required for this issue to be exploitable. Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability. When the BGP session flaps on the NSR-enabled router, the device enters GR-helper/LLGR-helper mode due to the peer having negotiated GR/LLGR-restarter capability and the backup BGP requests for replication of the GR/LLGR-helper session, master BGP schedules, and initiates replication of GR/LLGR stale routes to the backup BGP. In this state, if the BGP session with the BGP peer comes up again, unsolicited replication is initiated for the peer without cleaning up the ongoing GR/LLGR-helper mode replication. This parallel two instances of replication for the same peer leads to the assert if the BGP session flaps again. This issue affects: Juniper Networks Junos OS * All versions earlier than 20.4R3-S9; * 21.2 versions earlier than 21.2R3-S7; * 21.3 versions earlier than 21.3R3-S5; * 21.4 versions earlier than 21.4R3-S5; * 22.1 versions earlier than 22.1R3-S4; * 22.2 versions earlier than 22.2R3-S3; * 22.3 versions earlier than 22.3R3-S1; * 22.4 versions earlier than 22.4R2-S2, 22.4R3; * 23.2 versions earlier than 23.2R1-S1, 23.2R2. Juniper Networks Junos OS Evolved * All versions earlier than 21.3R3-S5-EVO; * 21.4 versions earlier than 21.4R3-S5-EVO; * 22.1 versions earlier than 22.1R3-S4-EVO; * 22.2 versions earlier than 22.2R3-S3-EVO; * 22.3 versions earlier than 22.3R3-S1-EVO; * 22.4 versions earlier than 22.4R2-S2-EVO, 22.4R3-EVO; * 23.2 versions earlier than 23.2R1-S1-EVO, 23.2R2-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

A race condition in Juniper Junos OS and Junos OS Evolved's BGP session handling occurs when Non-Stop Routing (NSR) and Graceful Restart (GR) helper mode are both enabled. When BGP sessions flap repeatedly, the device can enter a state where two parallel GR/LLGR-helper replication instances run simultaneously for the same peer without proper cleanup, triggering an assertion failure that crashes the rpd routing daemon.

MitigationDisable Non-Stop Routing (NSR) if not required, or upgrade to a fixed Junos OS/Evolved version. Note: SRX Series is not affected as NSR is not supported.

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:= 20.4= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2
Junos Os EvolvedOperating system
Affected:= 21.3= 21.4= 22.1= 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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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 'request system version' command to obtain the installed Junos version
    Affected if Version matches 20.4, 21.2, 21.3, 21.4, 22.1, 22.2, 22.3, 22.4, or 23.2 for Junos; or 21.3, 21.4, 22.1, 22.2, 22.3, 22.4, or 23.2 for Junos OS Evolved
  2. Verify NSR is enabled
    Run 'show chassis routing-engine' and look for 'Non-Stop Routing is Enabled' status, or check 'show configuration routing-options' for 'non-stop-routing' statement
    Affected if NSR is enabled in the configuration and operational status shows it as active
  3. Confirm Graceful Restart helper mode is enabled
    Run 'show configuration protocols bgp' and look for 'graceful-restart' or 'helper-disable' not present, or check 'show bgp neighbor' for GR helper capability
    Affected if Graceful Restart helper mode is enabled (helper is not disabled)
  4. Confirm BGP is configured
    Run 'show bgp summary' or 'show configuration protocols bgp' to verify BGP peers exist
    Affected if BGP is configured with at least one peer that can experience session flaps

You are affected if your Junos version matches the affected list, NSR is enabled, Graceful Restart helper mode is enabled, and BGP peers are configured that could experience repeated session flaps.

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

Disable Non-Stop Routing (NSR) if not required, or upgrade to a fixed Junos OS/Evolved version. Note: SRX Series is not affected as NSR is not supported.

Recommended fix High confidence

For Junos OS: 20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S3, 22.3R3-S1, 22.4R2-S2/22.4R3, 23.2R1-S1/23.2R2 or later. For Junos OS Evolved: 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S3-EVO, 22.3R3-S1-EVO, 22.4R2-S2-EVO/22.4R3-EVO, 23.2R1-S1-EVO/23.2R2-EVO or later.

  1. 1. Verify the device is running an affected Junos OS or Junos OS Evolved version by running 'show version'
  2. 2. Confirm that Non-Stop Routing (NSR) is enabled on the device with 'show routing process' or 'show configuration routing-options nonstop-routing'
  3. 3. Confirm that Graceful Restart (GR) helper mode is enabled (it is enabled by default) with 'show protocol bgp'
  4. 4. Schedule a maintenance window for the upgrade as it will require a system restart
  5. 5. Back up the current configuration with 'request system snapshot' or by exporting configuration via 'show configuration | display xml' or 'show configuration | save <filename>'
  6. 6. Download the appropriate fixed release for your platform from the Juniper Networks support portal
  7. 7. Upgrade the device using 'request system software add <package-name>' with the appropriate options for your hardware (e.g., 'request system software add /var/tmp/junos-xx.x.x.x.x-domestic.tgz reboot'
  8. 8. After reboot, verify the new Junos version is running with 'show version'
Caveat Standard Junos upgrade precautions apply: review release notes for breaking changes, test in lab first, and ensure compatibility with other network devices for BGP GR/LLGR capabilities

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,080
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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-2024-21585 in production — separate from our analysis above.

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