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CVE-2026-20323

8.3 · HIGH

A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software and Cisco Secure FTD Software could allow an unauthenticated, adjacent attacker to impersonate the p…

Published Sep 16, 2026CWE-295EPSS 0.13%

Overview

CVE-2026-20323 is a high-severity vulnerability. It was published on September 16, 2026 and has a CVSS 3.1 base score of 8.3 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.3, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software and Cisco Secure FTD Software could allow an unauthenticated, adjacent attacker to impersonate the peer device and obtain access at the level of the manager role, which is equivalent to root.

This vulnerability is due to improper management of the TLS certificate for the sftunnel management connection. An attacker could exploit this vulnerability by connecting to the sftunnel port using a crafted TLS certificate. A successful exploit could allow the attacker to become a registered sftunnel peer with root access.

Note: The attack is successful only if the sftunnel connection is down or the attack can disrupt the sftunnel connection long enough to execute the attack.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refsec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmcftd-sftun-multivulns-WGVHOrN3

How CyberStrike helps

Frequently asked questions

What is CVE-2026-20323?

CVE-2026-20323 is a high-severity vulnerability. It was published on September 16, 2026 and has a CVSS 3.1 base score of 8.3 (HIGH).

How severe is CVE-2026-20323?

This vulnerability has a CVSS 3.1 base score of 8.3, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-20323?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-20323?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-20323 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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