Junos OS and Junos OS Evolved: Stack-based buffer overflow in BGP routing daemon
Summary
A stack-based buffer overflow in the BGP routing daemon (rpd) of Junos OS and Junos OS Evolved allows a configured BGP flowspec peer to compromise the routing engine or cause a denial of service of the routing daemon. The flaw is triggered by a specially malformed flowspec NLRI and only applies when BGP update-threading is enabled. Juniper is not aware of any malicious exploitation.
Affected
- Junos OS: 0 to below 23.2R2-S7.7; 23.4 to below 23.4R2-S8.13; 24.2 to below 24.2R2-S5.5; 24.4 to below 24.4R2-S5; 25.2 to below 25.2R2-S2; 25.4 to below 25.4R1-S3; 26.2 to below 26.2R1-S2
- Junos OS Evolved: 0 to below 23.2R2-S7.7-EVO; 23.4 to below 23.4R2-S8.11-EVO; 24.2 to below 24.2R2-S5.6-EVO; 24.4 to below 24.4R2-S5-EVO; 25.2 to below 25.2R2-S2-EVO; 25.4 to below 25.4R1-S3-EVO; 26.2 to below 26.2R1-S2-EVO; 23.4X100; 25.2X100 to below 25.2X100-D35-EVO; 25.4X300 to below 25.4X300-D40-EVO
- Default configuration is not affected. Required: BGP update-threading enabled and flowspec family configured on a BGP peer
Fixed in
- 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
Workaround
There are no known workarounds.
Exploitation
- Juniper SIRT is not aware of any malicious exploitation.
- CISA SSVC: exploitation none, automatable yes, technical impact total.
Our recommendation
- Check whether BGP update-threading and flowspec are configured on your Junos devices
- Restrict BGP flowspec peering to trusted peers only
- Update to a fixed release listed above and verify the versions against JSA112187 before scheduling
- Monitor the routing engine and rpd for crashes or unexpected restarts
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Juniper Security Advisory JSA112187 supportportal.juniper.net
- CVE-2026-102178 Strix AI www.strix.ai
- CVE-2026-102178 threatint record cve.threatint.com
- CVE-2026-102178 OpenCVE app.opencve.io
- CVE-2026-102178 BGP flowspec write-up dev.to
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 01:55.
Original description (NVD)
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.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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