CVE-2026-20323

Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Unauthorized Authentication Bypass Vulnerability

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Published Sep 16, 2026 CVSS 3.1 · 8.3 High EPSS < 1% KEV · Not listed
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&nbsp;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

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Cisco
Cisco secure Firewall Management Center
Cisco secure Firewall Threat Defense
Vendors & Products Cisco
Cisco secure Firewall Management Center
Cisco secure Firewall Threat Defense
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}
Type Values Removed Values Added
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&nbsp;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.
Title Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Unauthorized Authentication Bypass Vulnerability
Weaknesses CWE-295
References
Metrics cvssV3_1

{'score': 8.3, 'vector': 'CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H'}
Weaknesses

Sources

Status
PUBLISHED
Assigner
cisco
Published
Updated
Sep 17, 2026, 11:39 AM
Reserved
Oct 8, 2025, 11:59 AM

View source JSON

Updated
Sep 17, 2026, 11:31 AM

JSON

Status
Awaiting Analysis
Published
Sep 16, 2026, 9:17 PM
Modified
Sep 18, 2026, 1:28 PM

View source JSON

No data.

Updated
Sep 18, 2026, 9:51 PM

JSON