CVE-2026-20006 Cisco Firepower Threat Defense Software and Cisco FirePOWER Services TLS with Snort 3 Denial of Service Vulnerability
An unauthenticated remote attacker can cause a denial of service by sending crafted TLS packets to Cisco Secure Firewall Threat Defense devices.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20006?
CVE-2026-20006 is a medium-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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
Which versions are affected by CVE-2026-20006?
It affects 1 product.
Products include Cisco Secure Firewall Threat Defense.
How do I fix CVE-2026-20006?
No fix has been published for CVE-2026-20006 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-20006 being exploited?
There is no known exploitation of CVE-2026-20006 in the wild and no public exploit code.
Other vulnerabilities in Cisco Secure Firewall Threat Defense
- CVE-2024-20412 Hardcoded credentials in Cisco Firepower Threat Defense Software
- CVE-2024-20330 Memory corruption in Cisco Firepower Threat Defense Software
- CVE-2024-20339 Cisco Firepower Threat Defense Software for Firepower 2100 Series TLS Denial of Service Vulnerability
- CVE-2024-20351 Cisco Firepower Threat Defense Software Snort Firewall Denial of Service Vulnerability
- CVE-2023-20083 Denial of service in Cisco Firepower Threat Defense Software
Sources
Also known as GHSA-mh5f-h37q-2qm8.