CVE-2026-101951
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Improper Input Validation in Juniper Junos OS BGP Peer

Publication date: 2026-10-14

Last updated on: 2026-10-14

Assigner: Juniper Networks, Inc.

Description
An Improper Validation of Consistency within Input vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-adjacent configured BGP peer to cause a denial of service by sending a specifically malformed BGP MCAST-TREE update and this NLRI is then attempted to be readvertised.

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Meta Information

Published
2026-10-14
Last Modified
2026-10-14
Generated
2026-10-19
AI Q&A
2026-10-15
EPSS Evaluated
2026-10-18
NVD
CVE-2026-101951
EUVD
EUVD-2026-101449

Affected Vendors & Products

Showing 17 associated CPEs
Vendor Product Version / Range
Juniper Networks Junos OS 0
Juniper Networks Junos OS 23.4
Juniper Networks Junos OS 24.2
Juniper Networks Junos OS 24.4
Juniper Networks Junos OS 25.2
Juniper Networks Junos OS 25.4
Juniper Networks Junos OS 26.2
Juniper Networks Junos OS Evolved 0
Juniper Networks Junos OS Evolved 23.4
Juniper Networks Junos OS Evolved 24.2
Juniper Networks Junos OS Evolved 24.4
Juniper Networks Junos OS Evolved 25.2
Juniper Networks Junos OS Evolved 25.4
Juniper Networks Junos OS Evolved 26.2
Juniper Networks Junos OS Evolved 23.4X100
Juniper Networks Junos OS Evolved 25.2X100
Juniper Networks Junos OS Evolved 25.4X300

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-1288 The product receives a complex input with multiple elements or fields that must be consistent with each other, but it does not validate or incorrectly validates that the input is actually consistent.

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Executive Summary

This vulnerability is an Improper Validation of Consistency within Input issue in Juniper Networks Junos OS and Junos OS Evolved. It allows a network-adjacent configured BGP peer to cause a denial of service by sending a malformed BGP MCAST-TREE update. The router then attempts to readvertise this malformed update, leading to a crash or service disruption.

Detection Guidance

This vulnerability can be detected by monitoring for malformed BGP MCAST-TREE updates. Check BGP logs for unusual NLRI advertisements and verify consistency in routing protocol daemon (rpd) processing. Juniper recommends inspecting BGP session logs and using 'show bgp neighbor' commands to detect anomalies.

Impact Analysis

If exploited, this vulnerability can cause your network devices running Junos OS or Junos OS Evolved to crash or become unresponsive. This leads to service outages, loss of connectivity, and potential disruption of critical network functions like routing and data transmission.

Compliance Impact

The vulnerability causes a denial of service by malformed BGP MCAST-TREE updates, which may disrupt network availability. This could impact compliance with standards requiring continuous availability, such as HIPAA for healthcare systems or GDPR for data processing operations, by potentially leading to service unavailability.

Mitigation Strategies

Apply the latest Junos OS or Junos OS Evolved security patches from Juniper Networks to address the BGP MCAST-TREE update validation issue. Disable BGP peering sessions until patches are applied if possible.

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