May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and fixed after the Cisco Catalyst SD-WAN Controller Authentication Bypass Vulnerability was disclosed in February 2026. This new advisory is for a new vulnerability in the control connection handshaking. The Indicators of Compromise section of this advisory includes Show Control Connections guidance to help with system checks. A 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, could allow an unauthenticated, remote attacker to bypass authentication and obtain administrative privileges on an affected system. 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 the affected system. A successful exploit could allow the attacker to log in to an affected Cisco Catalyst SD-WAN Controller as an internal, high-privileged, non- root user account. Using this account, the attacker could access NETCONF, which would then allow the attacker to manipulate network configuration for the SD-WAN fabric. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. Important: To preserve possible indicators of compromise, customers should issue the request admin-tech command from each of the control components in the SD-WAN deployment before upgrading. After the admin-tech file has been collected, software should be upgraded at the earliest opportunity. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-rpa2-v69WY2SW <br/>Security Impact Rating: Critical <br/>CVE: CVE-2026-20182