CVE-2026-20323
HighCVSS 8.3Exploitation Probability (EPSS)
Low risk0th percentile - higher than 0% of all known CVEs
Summary
Vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC and FTD Software allows an unauthenticated, adjacent attacker to impersonate the peer device and gain access at the manager role level (root). This is due to improper management of the TLS certificate for the sftunnel connection.
Risk Assessment
An attacker can gain full root access to the device, potentially leading to complete system and data compromise. The attack is only successful if the sftunnel connection is down or the attacker can disrupt it long enough.
Recommendation
Apply the software update from Cisco that fixes this vulnerability and monitor sftunnel connections for unauthorized attempts.
Other vulnerabilities in Cisco Secure FMC/FTD Software
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS