CVE-2026-102027

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Incorrect Buffer Size Calculation in Juniper Junos OS RPD

Publication date: 2026-10-14

Last updated on: 2026-10-16

Assigner: Juniper Networks, Inc.

Description

An Incorrect Calculation of Buffer Size vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a configured eBGP neighbor to cause an rpd crash via BGP labeled-unicast UPDATEs when the affected multipath features are enabled.

CVSS Scores

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Meta Information

Published

2026-10-14

Last Modified

2026-10-16

Generated

2026-10-19

AI Q&A

2026-10-15

EPSS Evaluated

2026-10-18

NVD

CVE-2026-102027

EUVD

EUVD-2026-101352

Affected Vendors & Products

Vendor	Product	Version / Range
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 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 25.2X100
Juniper	Networks	Junos OS Evolved 25.4X300

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-131	The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

Attack-Flow Graph

Executive Summary

This vulnerability is an Incorrect Calculation of Buffer Size issue in Juniper Networks Junos OS and Junos OS Evolved. It occurs in the routing protocol daemon (rpd) and is triggered when a configured eBGP neighbor sends BGP labeled-unicast UPDATEs with multipath features enabled. This causes an rpd crash due to improper buffer size handling.

Detection Guidance

This vulnerability can be detected by monitoring for rpd crashes or unexpected behavior in Junos OS or Junos OS Evolved systems with multipath BGP features enabled. Check logs for BGP labeled-unicast UPDATEs causing crashes. Juniper recommends reviewing system logs and enabling debugging for BGP and rpd processes.

Impact Analysis

The vulnerability can lead to denial of service (DoS) by crashing the rpd, disrupting routing operations. This may cause network instability, loss of connectivity, or service outages for affected systems running vulnerable Junos OS or Junos OS Evolved versions.

Compliance Impact

This vulnerability does not directly impact compliance with GDPR, HIPAA, or similar standards as it relates to network routing protocol crashes rather than data protection or privacy controls. Compliance risks would arise only if the vulnerability leads to service disruptions affecting regulated systems.

Mitigation Strategies

Disable multipath features for BGP labeled-unicast sessions and update Junos OS or Junos OS Evolved to the latest patched version as soon as possible.

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