Cisco ASA and FTD Firewalls Affected by DoS Vulnerability in SSL VPN Already Exploited in the Wild

Cisco Systems has disclosed a denial-of-service vulnerability affecting its Cisco Secure Firewall ASA and Cisco Secure Firewall FTD products. The flaw, tracked as CVE-2026-76418, resides in the SSL VPN feature and carries a CVSS v3.1 base score of 8.6, rated High severity. When secondary authentication is configured for tunnel groups in the SSL remote access VPN login service, an attacker can send a specially crafted request during the connection process to reboot the device without any authentication. This triggers a service denial state on the affected appliance. Cisco confirmed active exploitation of the issue in October 2026 and has released patches for both products. Organizations are strongly advised to apply the updates immediately to prevent further abuse.

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Cisco Systems has disclosed a denial-of-service vulnerability in its Cisco Secure Firewall ASA and Cisco Secure Firewall FTD products. The flaw, identified as CVE-2026-76418, affects the SSL VPN functionality and has already been exploited in the wild.

According to the security advisory published on 28 October 2026, the vulnerability impacts configurations where secondary authentication is enabled for tunnel groups within the SSL remote access VPN login service. An unauthenticated attacker can send a crafted request during the SSL VPN connection process, forcing the device to reboot and causing a service denial condition.

The CVSS v3.1 base score for the issue is 8.6, placing it in the High severity category. Cisco confirmed exploitation activity targeting the products in October 2026.

Patches addressing the vulnerability are now available for both Cisco Secure Firewall ASA and Cisco Secure Firewall FTD. The vendor urges all customers to apply the updates without delay to mitigate the risk of further attacks.

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