CVE-2026-20006
Cisco Firepower Threat Defense Software and Cisco FirePOWER Services TLS with Snort 3 Denial of Service Vulnerability
Description
A vulnerability in the TLS cryptography functionality of the Snort 3 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to unexpectedly restart, resulting in a denial of service (DoS) condition. This vulnerability is due to improper implementation of the TLS protocol. An attacker could exploit this vulnerability by sending a crafted TLS packet to an affected system. A successful exploit could allow the attacker to cause a device that is running Cisco Secure FTD Software to drop network traffic, resulting in a DoS condition. Note: TLS 1.3 is not affected by this vulnerability.
Weakness: CWE-388
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
Vendor-reported products (1)
- Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
Vendor advisory
Cisco Secure Firewall Threat Defense Software TLS with Snort 3 Detection Engine Denial of Service Vulnerability
Cisco’s rating: Medium (advisory CVSS 5.8) · Published Mar 4, 2026
Bug ID: CSCwn73801
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from