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CVE-2026-76504

Critical CVSS 9.8 Known exploited

Published 2026-09-30 · last changed 2026-10-03 · added to CISA KEV 2026-09-30

This one is being exploited in the wild.

CISA added CVE-2026-76504 to the Known Exploited Vulnerabilities catalog on 2026-09-30. Federal agencies are required to remediate it on a deadline. If you have affected machines, this is the class of finding that moves ahead of the rest of the queue.

The fix

We hold no Microsoft remediation data for CVE-2026-76504, which normally means it isn't a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release. NVD lists the affected software below.

What it is

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 software

As listed by NVD. Version ranges vary per entry, so check the NVD record before treating a product name here as a yes or a no for a specific version.

Sources

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