Cisco patches firewall zero-day that attackers exploit to crash SSL VPN devices

Summary

Cisco released security updates to fix a denial-of-service zero-day in its Adaptive Security Appliance (ASA) and Threat Defense (FTD) software. Attackers are exploiting the flaw to remotely crash vulnerable firewall devices. The Hacker News later reported that CISA added this Cisco firewall flaw, along with a GitLab remote code execution flaw, to its Known Exploited Vulnerabilities catalog, citing evidence of active exploitation.

Timeline

1. BleepingComputer

   29 Oct 2026, 11:10 UTCSource ↗

   BleepingComputer reports that Cisco released security updates to patch a denial-of-service zero-day in ASA and FTD software that attackers are exploiting to remotely crash vulnerable firewall devices.

2. The Hacker News

   30 Oct 2026, 07:27 UTCSource ↗

   The Hacker News reports that CISA added a Cisco firewall denial-of-service flaw and a GitLab remote code execution flaw to its Known Exploited Vulnerabilities catalog, citing evidence of active exploitation.