cisco-sa-sdwan-webauth-xr8beuuU: Cisco Catalyst SD-WAN Manager API Authentication Bypass Vulnerability

A vulnerability in the API session-based authentication management of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user.This vulnerability is due to improper handling of URI encoding in an HTTP request, which allows the request to bypass an authentication rule that is intended to restrict access to a specific API endpoint. An attacker could exploit this vulnerability by sending a crafted HTTP request to the API of the affected system. A successful exploit could allow the attacker to bypass authentication and gain access to the API as the admin user.Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.Live Protect ShieldCisco has released a Live Protect shield for CVE-2026-76504 to provide temporary security coverage to allow time for software upgrade planning, including preserving any information that customers may require for governance or compliance purposes.This shield offers only temporary partial protection. The only way to remediate this vulnerability is to upgrade to the first fixed software release, as noted in the Fixed Releases section of this advisory. Cisco strongly recommends prioritizing system upgrades and scheduling them as soon as possible to ensure remediation.Before deploying the shield, read the following information:Side Effects/Limitation: If this shield is appliedA legitimate user with URI encoding might not be able to login to SDWAN Manager.For more information about Live Protect for Cisco Catalyst SD-WAN, see https://www.cisco.com/c/en/us/td/docs/routers/sdwan/26x-later/network-monitoring/network-monitoring-guide/live-protect-for-cisco-catalyst-sd-wan.html.This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU