CVE-2025-20362
Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Missing Authorization Vulnerability
Update: On November 5, 2025, Cisco became aware of a new attack variant against devices running Cisco Secure ASA Software or Cisco Secure FTD Software releases that are affected by CVE-2025-20333 and CVE-2025-20362. This attack can cause unpatched devices to unexpectedly reload, leading to denial of service (DoS) conditions. Cisco strongly recommends that all customers upgrade to the fixed software releases that are listed in the Fixed Software ["#fs"] section of this advisory. A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to access restricted URL endpoints that are related to remote access VPN that should otherwise be inaccessible without authentication.
The KEV due date refers to the deadline by which FCEB agencies are expected to review and begin implementing the guidance outlined in Emergency Directive (ED) 25-03 (URL listed below in Notes). Agencies must follow the mitigation steps provided by CISA (URL listed below in Notes) and vendor’s instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available. Deadline for federal agencies: 2025-09-26.
3 articles across 3 outlets · first covered Apr 24, 2026 · latest Apr 25, 2026
Associated threat actors
Coverage timeline
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FIRESTARTER backdoor persists on patched Cisco ASA devicessecurityaffairs.com · Apr 25, 2026
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Cisco ASA Backdoor FIRESTARTER Persists After Patches, NCSC Warnsthehackernews.com · Apr 24, 2026
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US Agency Hit by Firestarter Backdoor on Cisco Firepower Gearwww.securityweek.com · Apr 24, 2026