CVE-2026-49494 Details

A denial-of-service vulnerability has been identified in Comodo Internet Security versions through 12.3.4.8162. The issue resides in the firewall driver Inspect.sys, which contains an integer underflow in its IPv6 packet parser. This parser improperly decrements an unsigned 64-bit payload-length value from the IPv6 fixed header, without validating it. As a result, a packet with a declared payload length smaller than the total length of its extension headers can cause the value to underflow, approaching the maximum limit of a 64-bit integer. Exploitation of this vulnerability leads to an out-of-bounds read and, on a separate code path, an oversized memory copy in the Windows kernel, occurring at DISPATCH_LEVEL. This exploitation causes the system to crash, resulting in a Blue Screen of Death (BSOD). Notably, the vulnerability can be triggered by a remote, unauthenticated attacker sending a single crafted IPv6 packet, even to a host with all ports blocked.