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JunosOperating system · Juniper

CVE-2025-21602

MEDIUM · 6.5 CVSS v3.1 Published 2025-01-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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 the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker sending a specific BGP update packet to cause rpd to crash and restart, resulting in a Denial of Service (DoS). Continuous receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability. This issue affects Junos OS:  * from 21.4 before 21.4R3-S9,  * from 22.2 before 22.2R3-S5,  * from 22.3 before 22.3R3-S4, * from 22.4 before 22.4R3-S5,  * from 23.2 before 23.2R2-S3,  * from 23.4 before 23.4R2-S3,  * from 24.2 before 24.2R1-S2, 24.2R2;  This issue does not affect versions prior to 21.1R1. Junos OS Evolved:  * from 21.4 before 21.4R3-S9-EVO,  * from 22.2 before 22.2R3-S5-EVO,  * from 22.3 before 22.3R3-S4-EVO, * from 22.4 before 22.4R3-S5-EVO,  * from 23.2 before 23.2R2-S3-EVO,  * from 23.4 before 23.4R2-S3-EVO,  * from 24.2 before 24.2R1-S2-EVO, 24.2R2-EVO. This issue does not affect versions prior to 21.1R1-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 vulnerability in Juniper Junos OS and Junos OS Evolved's routing protocol daemon (rpd) allows an unauthenticated adjacent attacker to send a specially crafted BGP update packet that causes rpd to crash and restart, creating a denial of service. Continuous receipt of the malicious packet sustains the DoS condition. The vulnerability affects both iBGP and eBGP across IPv4 and IPv6.

MitigationApply the vendor-supplied software updates (21.4R3-S9, 22.2R3-S5, 22.3R3-S4, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, 24.2R1-S2 or 24.2R2 and later) to all affected devices. Consider implementing BGP route filtering or prefix limits as interim mitigation if immediate patching is not 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
JunosOperating system
Affected:= 21.2= 21.4= 22.2= 22.3= 22.4= 23.2= 23.4= 24.2
Junos Os EvolvedOperating system
Affected:= 21.2= 21.4= 22.2= 22.3= 22.4= 23.2= 23.4= 24.2

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. Identify the Junos OS version
    Run 'show version' on the device CLI to obtain the exact Junos OS version installed
    Affected if The installed version matches any of the affected versions: 21.2, 21.4, 22.2, 22.3, 22.4, 23.2, 23.4, or 24.2
  2. Confirm BGP is configured
    Run 'show configuration protocols bgp' to display the BGP configuration and verify BGP is actively configured
    Affected if BGP protocol is configured and enabled on the device
  3. Verify rpd is running
    Run 'show system processes routing' or check process monitoring to confirm the routing protocol daemon (rpd) is active
    Affected if The rpd process is running and handling BGP sessions

The device is affected if it runs any of the listed Junos OS or Junos OS Evolved versions and has BGP protocol enabled with the rpd daemon active to process 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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied software updates (21.4R3-S9, 22.2R3-S5, 22.3R3-S4, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, 24.2R1-S2 or 24.2R2 and later) to all affected devices. Consider implementing BGP route filtering or prefix limits as interim mitigation if immediate patching is not feasible.

Recommended fix High confidence

Upgrade to the latest S-release or R-release in your current train (e.g., 21.4R3-S9, 22.2R3-S5, 22.3R3-S4, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, or 24.2R2)

  1. 1. Identify the current Junos OS or Junos OS Evolved version using `show version` command
  2. 2. Determine the appropriate upgrade path based on current version: if on 21.4x, upgrade to 21.4R3-S9 or later; if on 22.2x, upgrade to 22.2R3-S5 or later; if on 22.3x, upgrade to 22.3R3-S4 or later; if on 22.4x, upgrade to 22.4R3-S5 or later; if on 23.2x, upgrade to 23.2R2-S3 or later; if on 23.4x, upgrade to 23.4R2-S3 or later; if on 24.2x, upgrade to 24.2R1-S2 or 24.2R2 or later
  3. 3. Download the appropriate junos-srx orevo package from the Juniper support portal matching the target version
  4. 4. Validate the software package integrity using MD5/SHA checksums from Juniper support
  5. 5. Upload the software package to the device using `file copy` or FTP/SCP
  6. 6. For Junos OS: install the upgrade using `request system software add <package> no-validate reboot`
  7. 7. For Junos OS Evolved: use `request system software add <package>` followed by `request system reboot`
  8. 8. After reboot, verify the new version with `show version` and confirm BGP peering is operational with `show bgp summary`
Caveat Standard Junos upgrade considerations apply - ensure configuration compatibility and plan maintenance window for reboot

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
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2025-21602 in production — separate from our analysis above.

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