CISA Releases AR26-113A on the FIRESTARTER Backdoor: What It Means for Cisco ASA, FTD, and Firepower — and How Forward Can Help
If you manage Cisco ASA, Firepower, or Secure Firewall anywhere in your environment, this one demands your immediate attention.On April 23, 2026, CISA published Analysis Report AR26-113A, a malware analysis report on a backdoor known as FIRESTARTER. The report — issued jointly with the UK’s National Cyber Security Centre — confirms that at least one U.S. federal agency was compromised through a Cisco Firepower device, and that the attackers used FIRESTARTER to maintain persistent access even after the device was patched and rebooted. CISA has urged every organization running Cisco Secure Firewall ASA or Firepower Threat Defense (FTD) software to assess exposure now.This isn’t a brand-new vulnerability story — the underlying CVEs have been in CISA’s Known Exploited Vulnerabilities (KEV) catalog since September 25, 2025. What’s new is the depth of evidence about how the ArcaneDoor threat actor (tracked by Cisco Talos as UAT-4356) is operating after initial exploitation, and just how per