CVE-2009-2055: Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability

Medium severity, CVSS 5.9. Actively exploited: in CISA KEV since 2022-03-25. EPSS: 3.3% chance of exploitation in the next 30 days.

Cisco IOS XR 3.4.0 through 3.8.1 allows remote attackers to cause a denial of service (session reset) via a BGP UPDATE message with an invalid attribute, as demonstrated in the wild on 17 August 2009.

Affected products

• Cisco IOS XR: version 3.4 only; version 3.4.0 only; version 3.4.1 only; version 3.4.2 only; version 3.4.3 only; version 3.5 only; …

Published 2009-08-19. Last modified 2026-06-16.