CVE-2026-20121

Medium CVSS 5.3

Published 2026-09-16 · last changed 2026-09-18

The fix

We hold no Microsoft remediation data for CVE-2026-20121, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

A vulnerability in the access control list (ACL) Object Group Search (OGS) implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured access controls. This vulnerability is due to a logic error in populating group access control policies (ACPs) with OGS configured. An attacker could exploit this vulnerability by sending traffic that should be blocked through the device. A successful exploit could allow the attacker to bypass access controls and reach devices in protected networks.

Sources

NVD record for CVE-2026-20121

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