The US Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2026-76504, a Cisco Catalyst SD-WAN Manager Hex Encoding Vulnerability, to its Known Exploited Vulnerabilities (KEV) catalog on September 30, 2026. CISA adds a flaw to the catalog when it has reliable evidence that attackers are exploiting it in the wild.
What CISA says
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.
— CISA KEV catalog entry for CVE-2026-76504
Key facts
| CVE | CVE-2026-76504 |
|---|---|
| Vendor / product | Cisco Catalyst SD-WAN Manager |
| Added to KEV | September 30, 2026 |
| Federal deadline | October 3, 2026 |
| Known ransomware use | Unknown |
| Weakness (CWE) | CWE-177 |
| CISA forensic triage | Yes |
| CVSS base score (NVD) | 9.8 Critical |
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Who has to act, and by when
US federal civilian executive branch agencies are required to remediate the vulnerability by October 3, 2026. CISA urges all organizations to prioritize KEV-listed flaws as part of their vulnerability management.
CISA’s required action for this entry:
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
References
- CISA Known Exploited Vulnerabilities Catalog https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- NIST NVD — CVE-2026-76504 https://nvd.nist.gov/vuln/detail/CVE-2026-76504
- sec.cloudapps.cisco.com https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU
- www.cisa.gov https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- www.cisa.gov https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk