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
31.2th percentile
Discovered by
Vendor
Vendor-published field
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 products (1)
  • Cisco · Cisco Secure Firewall Threat Defense (FTD) Software

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