CVE-2026-76504

critical

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.

https://www.cisa.gov/news-events/alerts/2026/09/30/cisa-adds-one-known-exploited-vulnerability-catalog

https://www.bleepingcomputer.com/news/security/cisco-warns-of-new-sd-wan-authentication-bypass-zero-day-exploited-in-attacks/

https://thehackernews.com/2026/09/cisco-warns-of-attackers-exploiting.html

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

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-89950

Details

Source: Mitre, NVD

Published: 2026-09-30

Updated: 2026-10-01

Known Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 9.8

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: Critical

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability of Interest

Detections

Analytics