CVE-2026-20323

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.

CVSS v3 8.3 HIGH

8.3^/10

CVSS v3 : HIGH

Vector :

Exploitability : 1.6 / Impact : 6.0

Attack Vector ADJACENT_NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope CHANGED

References

Link	Resource
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmcftd-sftun-multivulns-WGVHOrN3

Configurations

No configuration.

History

16 Sep 2026, 21:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-16 21:17

Updated : 2026-09-18 13:28

NVD link : CVE-2026-20323

Mitre link : CVE-2026-20323

CVE.ORG link : CVE-2026-20323

JSON object : View

Products Affected

No product.

CWE

CWE-295

Improper Certificate Validation

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"published": "2026-09-16T21:17:10.313", "references": [{"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmcftd-sftun-multivulns-WGVHOrN3", "source": "psirt@cisco.com"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "psirt@cisco.com", "description": [{"lang": "en", "value": "CWE-295"}]}], "descriptions": [{"lang": "en", "value": "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.\r\n\r\nThis 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.\r\nNote: 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."}], "lastModified": "2026-09-18T13:28:28.567", "sourceIdentifier": "psirt@cisco.com"}