CVE-2019-16018: Cisco IOS XR

Medium severity, CVSS 6.5. EPSS: 1.1% chance of exploitation in the next 30 days.

A vulnerability in the implementation of Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of a BGP update message that contains crafted EVPN attributes. An attacker could indirectly exploit the vulnerability by sending BGP EVPN update messages with a specific, malformed attribute to an affected system and waiting for a user on the device to display the EVPN operational routes’ status. If successful, the attacker could cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic only from explicitly defined peers. To exploit this vulnerability, the malicious BGP update message would need to come from a configured, valid BGP peer, or would need to be injected by the attacker into the victim's BGP network on an existing, valid TCP connection to a BGP peer.

Affected products

• Cisco IOS XR: version 6.6.1 only; version 6.6.2 only; version 6.6.25 only; version 7.0.1 only

Published 2020-01-26. Last modified 2026-06-17.