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7.1

Junos OS Crashes from Malformed BGP Update

CVE-2026-33801 · published 3 months ago
Summary

A flaw in Junos OS and Junos OS Evolved allows an attacker to crash the system by sending a specific type of BGP update. This causes a service outage until the system restarts and reconnects. Affected versions should be upgraded to the latest patch to prevent this issue.

What to do
  • Update juniper networks junos os to version 25.2R2 or later.
  • Update juniper networks junos os evolved to version 25.2R2-EVO or later.
Affected software
VendorProductAffected versions
juniper networks junos os < 25.2R2
juniper networks junos os evolved < 25.2R2-EVO
Original advisory text
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 atta...
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.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
7.1 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-754Improper Check for Unusual or Exceptional Conditions
Timeline
Published9 Jul 2026
Updated3 Nov 2026
First seen9 Jul 2026
Sources
CVE-2026-33801 · NVD
CVE-2026-33801 · MITRE
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