Routing Protocol Vulnerability in Cisco IOS XR Software

CVE-2026-20074

What is CVE-2026-20074?

An input validation vulnerability exists in the Intermediate System-to-Intermediate System (IS-IS) multi-instance routing feature of Cisco IOS XR Software, which could allow an unauthenticated adjacent attacker to disrupt the IS-IS process. This disruption occurs when the attacker sends specially crafted IS-IS packets to a device after establishing adjacency. Successful exploitation may result in an unexpected restart of the IS-IS process, leading to a temporary loss of connectivity to advertised networks and potentially causing a denial of service.

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