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 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Solution

The following software releases have been updated to resolve this specific issue: Junos OS: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1, and all subsequent releases. Junos OS Evolved: 23.2R2-S7.7-EVO, 23.4R2-S8.11-EVO, 24.2R2-S5.6-EVO, 24.4R2-S5-EVO, 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4R2-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO, 26.2R2-EVO, 26.4R1-EVO, and all subsequent releases. Note: For Junos OS releases 23.2, 23.4, and 24.2, and Junos OS Evolved releases 23.2-EVO, 23.4-EVO, and 24.2-EVO, specific respins have been referenced. Previously published versions of these releases have been rebuilt to resolve the security vulnerabilities identified in this advisory.


Vendor Workaround

There are no known workarounds for this issue.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Juniper Networks
Juniper Networks junos Os
Juniper Networks junos Os Evolved
Vendors & Products Juniper Networks
Juniper Networks junos Os
Juniper Networks junos Os Evolved
Type Values Removed Values Added
Description 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.
Title Junos OS and Junos OS Evolved: When BGP update-threading is enabled a specifically malformed flowspec NLRI causes routing-engine compromise
Weaknesses CWE-121
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
juniper
Published
Updated
Oct 16, 2026, 4:35 PM
Reserved
Sep 28, 2026, 6:17 PM
Status
Awaiting Analysis
Published
Oct 14, 2026, 5:18 PM
Modified
Oct 16, 2026, 5:17 PM