CVE-2026-102178 PUBLISHED

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

Assigner: juniper
Reserved: 28.09.2026 Published: 14.10.2026 Updated: 14.10.2026

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.

Metrics

CVSS 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
CVSS Score: 9.3

Product Status

Vendor Juniper Networks
Product Junos OS
Versions Default: unaffected
  • affected from 0 to 23.2R2-S7.7 (excl.)
  • affected from 23.4 to 23.4R2-S8.13 (excl.)
  • affected from 24.2 to 24.2R2-S5.5 (excl.)
  • affected from 24.4 to 24.4R2-S5 (excl.)
  • affected from 25.2 to 25.2R2-S2 (excl.)
  • affected from 25.4 to 25.4R1-S3 (excl.)
  • affected from 26.2 to 26.2R1-S2 (excl.)
Vendor Juniper Networks
Product Junos OS Evolved
Versions Default: unaffected
  • affected from 0 to 23.2R2-S7.7-EVO (excl.)
  • affected from 23.4 to 23.4R2-S8.11-EVO (excl.)
  • affected from 24.2 to 24.2R2-S5.6-EVO (excl.)
  • affected from 24.4 to 24.4R2-S5-EVO (excl.)
  • affected from 25.2 to 25.2R2-S2-EVO (excl.)
  • affected from 25.4 to 25.4R1-S3-EVO (excl.)
  • affected from 26.2 to 26.2R1-S2-EVO (excl.)
  • Version 23.4X100 is affected
  • affected from 25.2X100 to 25.2X100-D35-EVO (excl.)
  • affected from 25.4X300 to 25.4X300-D40-EVO (excl.)

Affected Configurations

[ system processes routing bgp update-threading ] [ protocols bgp ... family inet/inet6 flow ]

Exploits

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

Workarounds

There are no known workarounds for this issue.

Solutions

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.

References

Problem Types

  • CWE-121 Stack-based Buffer Overflow CWE