CVE-2026-20295
Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Memory Exhaustion Denial of Service Vulnerability
Description
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.
Weakness: CWE-789
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
| Cisco | Cisco Secure Firewall Management Center Check your version | Network & Security Management | cna-assigner |
Vendor-reported products (2)
- Cisco · Cisco Secure Firewall Management Center (FMC)
- Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
Vendor advisory
cisco-sa-fmcftd-sftun-multivulns-WGVHOrN3
Cisco Secure Firewall Management Center and Secure Firewall Threat Defense Software sftunnel Vulnerabilities
Cisco’s rating: High (advisory CVSS 8.6) · Published Sep 16, 2026
Bug IDs: CSCws43281 , CSCwu16917
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from