CVE-2026-102178: BGP Flowspec Re-Advertisement Pushes a Stack Overflow Into the Junos Routing Engine

Flowspec was designed to let an operator distribute filters faster than a human can write them. CVE-2026-102178 abuses the re-advertisement half of that workflow: a peer sends a flowspec route, Junos selects it for redistribution, and the code that builds the outgoing update overflows a stack buffer in the BGP daemon.

Vulnerability overview

CVE-2026-102178 is a stack-based buffer overflow in the Border Gateway Protocol routing daemon of Juniper Networks Junos OS and Junos OS Evolved.…