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JunosOperating system · Juniper

CVE-2026-33801

MEDIUM · 6.5 CVSS v3.1 Published 2026-07-09
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 6 weeks old

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 Check for Unusual or Exceptional Conditions vulnerability in the routing protocol daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker sending a specific BGP update over an established BGP session to cause a Denial-of-Service (DoS). Upon receipt of a specifically malformed non-inet/inet6 unicast BGP update, an RPD crash and restart is triggered, which will cause a complete service outage until routing has reconverged. The rpd crash occurs before the update can be readvertised, so there is no downstream propagation. This issue affects: * Junos OS versions 25.2 before 25.2R2; * Junos OS Evolved versions 25.2 before 25.2R2-EVO. This issue doesn't affect Junos OS versions before 25.2R1 nor Junos OS Evolved versions before 25.2R1-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's routing protocol daemon (RPD) allows an adjacent, unauthenticated attacker with an established BGP session to send a specifically malformed non-inet/inet6 unicast BGP update that triggers an improper check for unusual conditions, causing rpd to crash and restart. This creates a complete service outage until routing reconverges. The issue affects Junos OS and Junos OS Evolved versions 25.2 before 25.2R2/25.2R2-EVO.

MitigationApply Juniper security patches 25.2R2 or later to affected devices. If immediate patching is not possible, consider BGP peering filtering or network segmentation to limit attack surface from adjacent attackers.

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:= 25.2
Junos Os EvolvedOperating system
Affected:= 25.2

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 version
    Execute 'show version' or 'show version detail' on the device CLI to retrieve the exact software version
    Affected if The version shows 25.2, 25.2R1, or any 25.2.x version before 25.2R2 (or 25.2R2-EVO for Evolved)
  2. Confirm BGP is configured
    Execute 'show bgp summary' or 'show bgp neighbor' to verify BGP is enabled and has at least one peer
    Affected if BGP is active with one or more established peering sessions
  3. Check for unicast address family configuration
    Execute 'show bgp neighbor <peer-ip> | match "Address Family"' to see which BGP address families are enabled
    Affected if The device has non-inet or non-inet6 unicast BGP address families configured (such as VPNv4, VPNv6, or route target)
  4. Verify the specific version falls within the vulnerable range
    Compare your installed version against: Junos 25.2 before 25.2R2, or Junos OS Evolved 25.2 before 25.2R2-EVO
    Affected if The version is exactly 25.2 or 25.2R1 (or equivalent x.x versions) and BGP with non-inet/inet6 unicast address families is configured

You are affected if the device runs Junos or Junos OS Evolved version 25.2 through 25.2R1 (or 25.2x before R2) AND has BGP peers with non-inet/inet6 unicast address families configured.

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 Juniper security patches 25.2R2 or later to affected devices. If immediate patching is not possible, consider BGP peering filtering or network segmentation to limit attack surface from adjacent attackers.

Recommended fix High confidence

Upgrade to Junos OS 25.2R2 or Junos OS Evolved 25.2R2-EVO

  1. 1. Identify whether the device is running Junos OS or Junos OS Evolved
  2. 2. Confirm current version is 25.2 (or between 25.2 and 25.2R1 for OS, or 25.2 and 25.2R1-EVO for Evolved) using 'show version'
  3. 3. Schedule a maintenance window for the upgrade (routing disruption will occur during upgrade)
  4. 4. Download the fixed release: Junos OS 25.2R2 or Junos OS Evolved 25.2R2-EVO from Juniper support portal
  5. 5. Upload the Junos upgrade package to the device using SCP or USB
  6. 6. For Junos OS: run 'request system software add <package>' and reboot using 'request system reboot'
  7. 7. For Junos OS Evolved: run 'request system software add <package>' and reboot using 'request system reboot'
  8. 8. After reboot, verify the new version is installed using 'show version'
Caveat Standard Junos upgrade considerations apply - brief routing disruption during the upgrade and reboot process; ensure configuration backup before upgrade

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

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33801 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data