CVE-2026-102178

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

State: Published
Severity: 9.3 Critical
Published: Oct 14, 2026
Updated: Oct 16, 2026
Reserved: Sep 28, 2026

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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.

Scores

CVSS	Score	Vector	Source
4.0	9.3 Critical	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	juniper
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	juniper

Weaknesses

CWE-121 Stack-based Buffer Overflow

Affected Products

Product	Versions
Junos OSJuniper Networks	before 23.2R2-S7.7Affected 23.4 to before 23.4R2-S8.13Affected 24.2 to before 24.2R2-S5.5Affected 24.4 to before 24.4R2-S5Affected 25.2 to before 25.2R2-S2Affected 25.4 to before 25.4R1-S3Affected 26.2 to before 26.2R1-S2Affected
Junos OS EvolvedJuniper Networks	before 23.2R2-S7.7-EVOAffected 23.4 to before 23.4R2-S8.11-EVOAffected 24.2 to before 24.2R2-S5.6-EVOAffected 24.4 to before 24.4R2-S5-EVOAffected 25.2 to before 25.2R2-S2-EVOAffected 25.4 to before 25.4R1-S3-EVOAffected 26.2 to before 26.2R1-S2-EVOAffected 23.4X100Affected 25.2X100 to before 25.2X100-D35-EVOAffected 25.4X300 to before 25.4X300-D40-EVOAffected

References

https://supportportal.juniper.net/JSA112187vendor-advisory

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