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

In short

Cisco Catalyst SD-WAN Manager has a weakness classified as improper handling of URL encoding (CWE-177). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-30. NVD lists CVSS 3.1 at 9.8 CRITICAL.

What it is

“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, retrieved 2026-11-01

“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.” — NVD, retrieved 2026-11-01

Who is affected

Cisco Catalyst SD-WAN Manager. NVD lists the following versions as affected:

• Versions before 20.9.10.1
• Versions from 20.12 inclusive, before 20.12.8.2
• Versions from 20.15 inclusive, before 20.15.6.1
• Versions from 20.18 inclusive, before 20.18.4.1
• Versions from 26.1 inclusive, before 26.1.2.1
• Versions version 26.2

Exploitation status

CISA KEV added: 2026-09-30. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-10-03.

Scores

NVD CVSS 3.1: 9.8 CRITICAL; vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source [email protected].

EPSS by FIRST: 38.93%; percentile 98.59; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-177.

Timeline

CISA required action

“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.” — CISA KEV

What to do

• Confirm whether you run Cisco Catalyst SD-WAN Manager and which version.
• Apply the vendor update or mitigation in the advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Mitigation, Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.