H-ISAC TLP White Vulnerability Advisory: New Attack Variant Targeting Cisco Secure Firewalls

On November 5, 2025, Cisco updated its security advisories regarding two critical vulnerabilities, CVE-2025-20333 and CVE-2025-20362, affecting Secure Firewall Adaptive Security Appliance (ASA) and Threat Defense (FTD) software, warning of a new, active attack variant.

This variant exploits both flaws to cause an unexpected device reload, resulting in a denial of service (DoS) condition on unpatched appliances. Cisco strongly recommends that users apply the released fixed software to prevent system compromise and service interruption.

Health-ISAC is sharing this to increase situational awareness and encourage organizations to assess their level of risk to these vulnerabilities.

View the detailed report below.