WORLDTECHCisco issues fixes for Secure Firewall VPN flaw used to crash devices
Cisco has reported that a high-severity flaw in the remote access SSL VPN service of its Secure Firewall products is being exploited to crash vulnerable devices. The weakness, tracked as CVE-2026-76418 and rated 8.6 in severity, is described in a report from one outlet that cites Cisco's advisory.
Flaw can force remote devices to reload
The weakness affects the remote access VPN service on Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) devices. According to the advisory, an unauthenticated remote attacker could send a specially built request while connecting to the SSL remote access VPN, causing the device to reload and leading to a denial of service.
Cisco traces the problem to logic errors that appear when secondary authentication is set up on a tunnel group.
Which configurations are exposed
The advisory states that a device is vulnerable if its running configuration includes the webvpn keyword and SSL VPN is active on at least one interface.
Cisco says no workarounds exist, which leaves the fixed software as the remedy it points to.
Fixed releases and the vendor
Fixed software is available in Secure Firewall ASA versions 9.16.4.104, 9.18.4.96, 9.20.4.50, 9.22.3.200, 9.23.1.48, 9.24.1.27, and 9.24.10.1. Cisco is a telecommunications and networking hardware company based in San Jose, and its products include network switches and wireless access points.
Open questions
- Are releases beyond the listed fixed versions also affected?
- How many devices have been crashed through exploitation so far?