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

- Exploited (CISA KEV): yes, added 2026-09-30
- Published: 2026-09-30
- CVSS: 9.8 CRITICAL (v3.1)
- EPSS: 38.9% (99th percentile)
- CWE: CWE-177

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | No public claim | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2026-10-21 | 21 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### F5

- 2026-10-21 · new · rule 200013230
  > Added: signature 200013230 "Cisco Catalyst SD-WAN Manager Authentication Bypass" (Authentication/Authorization Attacks, risk High), systems: Cisco. References: CVE-2026-76504.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2026-76504 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2026-76504