CVE-2025-20115: Cisco IOS XR

High severity, CVSS 8.6. EPSS: 0.9% chance of exploitation in the next 30 days.

A vulnerability in confederation implementation for the Border Gateway Protocol (BGP) in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to a memory corruption that occurs when a BGP update is created with an AS_CONFED_SEQUENCE attribute that has 255 autonomous system numbers (AS numbers). An attacker could exploit this vulnerability by sending a crafted BGP update message, or the network could be designed in such a manner that the AS_CONFED_SEQUENCE attribute grows to 255 AS numbers or more. A successful exploit could allow the attacker to cause memory corruption, which may cause the BGP process to restart, resulting in a DoS condition. To exploit this vulnerability, an attacker must control a BGP confederation speaker within the same autonomous system as the victim, or the network must be designed in such a manner that the AS_CONFED_SEQUENCE attribute grows to 255 AS numbers or more.

Affected products

• Cisco IOS XR: version 6.5.1 only; version 6.5.2 only; version 6.5.3 only; version 6.5.15 only; version 6.5.25 only; version 6.5.26 only; …

Published 2025-03-12. Last modified 2026-06-17.