Medium [CVE-2026-20006] Cisco Secure Firewall Threat Defense Software TLS with Snort 3 Detection Engine Denial of Service Vulnerability
This medium-severity Cisco advisory covers CVE-2026-20006 affecting Cisco Secure Firewall Threat Defense (FTD) Software 7.2.0.1, Cisco Secure Firewall Threat Defense (FTD) Software 7.2.1, Cisco Secure Firewall Threat Defense (FTD) Software 7.2.2.
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Summary
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…
Affected products named by the advisory: Cisco Secure Firewall Threat Defense (FTD) Software 7.2.0.1; Cisco Secure Firewall Threat Defense (FTD) Software 7.2.1; Cisco Secure Firewall Threat Defense (FTD) Software 7.2.2; Cisco Secure Firewall Threat Defense (FTD) Software 7.2.3; and 4 more.
- Scope: At the time of publication, this vulnerability affected Cisco products if they were running a vulnerable release of Cisco Secure FTD Software or Cisco FirePOWER Services and the following conditions were met:
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- As a workaround for this vulnerability, configure the device so that traffic from a specific TLS version is not blocked. To implement the workaround, complete the following steps:
- Log in to the Cisco Secure FMC Software web-based management interface.
- From the Policies menu, choose Access Control > SSL or Access Control > Decryption.
- Choose the appropriate SSL or decryption policy.
- Click the Edit pencil icon.
- Choose the appropriate rule.
- Click the Edit pencil icon.
- Click the Version tab.
- Ensure that all version check boxes are checked.
- Click Save to deploy the changes.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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