By Phil Muncaster
Publication Date: 2026-02-26 09:30:00
Government security agencies in the UK, US, Canada, Australia and New Zealand have urged Cisco customers to take immediate action to patch a critical zero-day bug in their SD-WAN kit that has been exploited since 2023.
CVE-2026-20127 is an authentication bypass vulnerability in the peering authentication in Cisco Catalyst SD-WAN Controller (formerly SD-WAN vSmart) and Cisco Catalyst SD-WAN Manager (formerly SD-WAN vManage).
According to Cisco, it could allow an unauthenticated, remote attacker to bypass authentication and obtain administrative privileges on an affected system. It has a maximum CVSS score of 10.0.
“This vulnerability exists because the peering authentication mechanism in an affected system is not working properly. An attacker could exploit this vulnerability by sending crafted requests to an affected system,” the Cisco advisory noted.
“A successful exploit could allow the attacker to log in to an affected Cisco Catalyst SD-WAN Controller as an internal,…
