CVEs / CVE-2026-76504

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

• Known exploited in the CISA KEV catalog since 30 Sep 2026
• critical 9.8 CVSS 3.1 (from the CNA)
• EPSS 38.9% chance of exploitation in the next 30 days, higher than 98% of CVEs (30 Oct 2026)
• Last changed at its sources 3 Oct 2026

Summary

Cisco Catalyst SD-WAN Manager contains a hex encoding vulnerability that could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user due to improper handling of URI encoding in an HTTP request.

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 and fixed versions

Exploitation

Severity

References

• CVE-2026-76504 on NVD
• CVE-2026-76504 in the CISA KEV catalog
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU (cited by CISA)
• https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk (cited by CISA)
• https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk (cited by CISA)
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU Mitigation, Vendor Advisory
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76504 US Government Resource