Cisco Catalyst SD-WAN Manager Authentication Bypass and Admin Privilege Escalation (CVE-2026-76504)
Executive & SecOps Summary
SECOPS ASSESSMENTCisco Catalyst SD-WAN Manager (formerly vManage) software
An unauthenticated, remote attacker can bypass authentication mechanisms and gain full administrative access to the system via crafted HTTP requests.
Immediately apply the official security patches provided by Cisco and restrict access to management interfaces using ACLs.
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND- Apply Security Updates: Upgrade to a fixed software release immediately via the Cisco Software Central portal.
- Restrict Management Access: Implement Infrastructure ACLs (iACLs) to ensure that only authorized, internal management networks can reach the SD-WAN Manager's web and API interfaces.
- WAF/IPS Deployment: Deploy signatures to detect suspicious URI encoding patterns (e.g., double encoding or path normalization bypass attempts) targeting the API endpoints.
# Monitor for suspicious URI patterns in logs
GET /api/v1/..%2f..%2fadmin/settings HTTP/1.1Stop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
This vulnerability (CVE-2026-76504) exists in the API session-based authentication management of Cisco Catalyst SD-WAN Manager due to improper handling of URI encoding in HTTP requests (CWE-177). An attacker can exploit this by sending a specially crafted HTTP request that bypasses the authentication rules intended to protect sensitive API endpoints. Successful exploitation allows the attacker to gain 'admin' user privileges without valid credentials. Given its status in the CISA KEV catalog and a high EPSS score of 0.94, this vulnerability represents a critical risk that is actively being targeted by threat actors.
Official Vendor Advisories & References
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.
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