CVE-2026-20006

Cisco Firepower Threat Defense Software and Cisco FirePOWER Services TLS with Snort 3 Denial of Service Vulnerability

Severity
Medium 5.8
CVSS 3.1
Exploited
Not listed
EPSS
0.004
30.0th percentile
Discovered by
Vendor
Published by the vendor
Published
Mar 4, 2026
Assigned by cisco

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 Secure Firewall Firewall / NGFW cna-assigner
Vendor-reported affected versions (1)
  • Cisco · Cisco Secure Firewall Threat Defense (FTD) Software