CVE-2026-20295: Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Memory Exhaustion Denial of Service Vulnerability
A vulnerability in the sftunnel inter-device communication protocol of Cisco Secure FMC Software and Cisco Secure FTD Software could allow an unauthenticated, remote attacker to exhaust the available memory of an affected device. This vulnerability is due to improper management of memory resources during sftunnel TLS connection setup. An attacker could exploit this vulnerability by sending crafted sftunnel TLS frames to an affected device during the connection setup. A successful exploit could allow the attacker to exhaust the available memory on the affected device, which could result in a DoS condition.
Affected Software
Event History
Frequently Asked Questions
Does an attacker need valid credentials or user interaction to exploit this issue?
No. The vulnerability is remotely exploitable without authentication or user interaction.
What network access does an attacker need?
The attacker must be able to send crafted sftunnel TLS frames to an affected device during sftunnel connection setup.
What is the expected impact of a successful attack?
A successful attack can exhaust available memory on the affected device, resulting in a denial-of-service condition. The provided information identifies no confidentiality or integrity impact.