CVE-2026-102178: Junos OS and Junos OS Evolved: When BGP update-threading is enabled a specifically malformed flowspec NLRI causes routing-engine compromise

Published Oct 14, 2026

Updated

A Stack-based Buffer Overflow vulnerability in the BGP routing daemon of Juniper Networks Junos OS and Junos OS Evolved allows a configured BGP flowspec peer to cause routing-engine compromise or a routing-daemon denial of service via flowspec route re-advertisement when BGP update-threading is enabled.

Affected Software

2 affected components

Juniper Networks Junos OS

Juniper Networks Junos OS Evolved

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 23.2R2-S7.7-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 23.4R2-S8.11-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 24.2R2-S5.6-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 24.4R2-S5-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 25.2R2-S2-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 25.2X100-D35-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 25.4R1-S3-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 25.4R2-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 25.4X300-D40-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 26.2R1-S2-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 26.2R2-EVO
Upgrade
Upgrade Juniper Junos OS Evolved to a version that resolves this vulnerability.
Fixed in 26.4R1-EVO
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 23.2R2-S7.7
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 23.4R2-S8.13
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 24.2R2-S5.5
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 24.4R2-S5
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 25.2R2-S2
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 25.4R1-S3
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 25.4R2
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 26.2R1-S2
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 26.2R2
Upgrade
Upgrade Juniper Junos OS to a version that resolves this vulnerability.
Fixed in 26.4R1

Event History

Oct 14, 2026

CVE Published

via MITRE·04:57 PM

Data Sourced

via MITRE·04:57 PM

RemedyDescriptionSeverityWeakness

Frequently Asked Questions

Which deployments are exposed to exploitation?

Affected deployments must use Junos OS or Junos OS Evolved, have BGP update-threading enabled, and have a configured BGP flowspec peer. The vulnerable processing occurs when flowspec routes are re-advertised.

What does an attacker need to exploit this issue?

An attacker needs to be a configured BGP flowspec peer capable of sending a specifically malformed flowspec NLRI. No separate authentication bypass or user interaction is described.

What is the potential impact of successful exploitation?

Successful exploitation can compromise the routing engine or cause a denial of service in the routing daemon. The stated impact includes high confidentiality, integrity, and availability effects.