CVE-2026-76504: Cisco Catalyst SD-WAN Manager Hex Encoding Vulnerability

Critical severity, CVSS 9.8. Actively exploited: in CISA KEV since 2026-09-30. EPSS: 1.8% chance of exploitation in the next 30 days.

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.

Affected products

• Cisco Catalyst SD-WAN Manager: before 20.9.10.1 (fixed in 20.9.10.1); from 20.12, before 20.12.8.2 (fixed in 20.12.8.2); from 20.15, before 20.15.6.1 (fixed in 20.15.6.1); from 20.18, before 20.18.4.1 (fixed in 20.18.4.1); from 26.1, before 26.1.2.1 (fixed in 26.1.2.1); version 26.2 only

Published 2026-09-30. Last modified 2026-10-03.