Cisco Firewall Vulnerabilities: Nearly 50,000 Devices at Immediate Risk from Active Zero-Day Attacks
In September 2025, nearly 50,000 Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) firewalls exposed to the public internet were found to be vulnerable to two critical zero-day flaws: CVE-2025-20333 and CVE-2025-20362. These vulnerabilities enabled remote, unauthenticated attackers to execute arbitrary code and access restricted VPN-related endpoints. Ongoing exploitation began before patches became available, targeting government and enterprise networks worldwide. Threat actors deployed custom malware (Line Viper) and a GRUB bootkit (RayInitiator), prompting emergency directives from agencies like CISA for immediate patching and device removal, especially for unsupported hardware. The lack of effective patch management and delayed response increased risk of network breaches, lateral movement, and data exfiltration. This incident underscores the persistent threat of infrastructure vulnerabilities and rapid weaponization of zero-day flaws targeting critical networking equipment. With attackers increasingly automating reconnaissance and exploitation, organizations face mounting regulatory and business pressure to maintain timely patching, robust monitoring, and segmented security controls.
Kill Chain