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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2026-09-30
• EPSS: 38.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-30 · updated 2026-10-03
• Weakness: CWE-177

Description

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; from 20.12 before 20.12.8.2; from 20.15 before 20.15.6.1; from 20.18 before 20.18.4.1; from 26.1 before 26.1.2.1; 26.2 — fixed in 20.12.8.2, 20.15.6.1, 20.18.4.1, 20.9.10.1, 26.1.2.1

How to fix

Upgrade to a fixed version: Cisco Catalyst SD-WAN Manager 20.12.8.2, 20.15.6.1, 20.18.4.1, 20.9.10.1. Check the vendor advisory for mitigations.

In the news

• Cisco Catalyst SD-WAN Manager API Authentication Bypass Vulnerability

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76504

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