Critical 0-Day Vulnerability in Comodo Internet Security Exposes Windows Systems

A zero-day vulnerability, named ComoDoS, has been discovered in Comodo Internet Security's firewall driver, Inspect.sys, allowing remote attackers to crash Windows systems using a single malformed IPv6 packet. The vulnerability was disclosed by security researcher Marcus Hutchins on June 3, 2026, after multiple attempts to notify the vendor went unanswered. This flaw bypasses all configured firewall rules, making it particularly dangerous. As of June 4, 2026, there has been no response from Comodo regarding a patch or mitigation strategy. The vulnerability affects users of Comodo Internet Security, potentially impacting millions of Windows systems worldwide. The lack of a fix and the ease of exploitation raise significant concerns for cybersecurity professionals.

Key Points: • ComoDoS vulnerability allows system crashes via a single malformed IPv6 packet. • Marcus Hutchins disclosed the flaw on June 3, 2026, after failed vendor notifications. • No response or patch from Comodo as of June 4, 2026, poses a critical risk.