CVE-2019-16020

Multiple vulnerabilities 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 vulnerabilities are due to incorrect processing of BGP update messages that contain crafted EVPN attributes. An attacker could exploit these vulnerabilities by sending BGP EVPN update messages with malformed attributes to be processed by an affected system. A successful exploit could allow the attacker to 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 these vulnerabilities, 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.

• CWE-399
• CWE-400

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200122-ios-xr-evpnVendor Advisory
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200122-ios-xr-evpnVendor Advisory

Published

Jan 26, 2020

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2019-16012A vulnerability in the web UI of Cisco SD-WAN Solution vMana…8.1
• CVE-2019-16015A vulnerability in the web-based management interface of the…6.1
• CVE-2019-16017A vulnerability in the Operations, Administration, Maintenan…6.8
• CVE-2019-16018A vulnerability in the implementation of Border Gateway Prot…6.5
• CVE-2019-16019Multiple vulnerabilities in the implementation of Border Gat…8.6
• CVE-2019-1602A vulnerability in the filesystem permissions of Cisco NX-OS…7.8
• CVE-2019-16021Multiple vulnerabilities in the implementation of Border Gat…7.5
• CVE-2019-16022Multiple vulnerabilities in the implementation of Border Gat…8.6
• CVE-2019-16023Multiple vulnerabilities in the implementation of Border Gat…7.5
• CVE-2019-16024A vulnerability in the web-based management interface of Cis…6.1
• CVE-2019-16025A vulnerability in the web framework of Cisco Emergency Resp…4.8
• CVE-2019-16026A vulnerability in the implementation of the Stream Control …5.9