Xcitium Client Security (XCS) before 13.8.2.10019 and Comodo Internet Security (CIS) through 12.3.4.8162 (fix expected by 2026 Q3) contain an integer underflow vulnerability in the firewall driver Inspect.sys that allows remote unauthenticated attackers to crash the system by sending a crafted IPv6 packet with a declared payload length smaller than the sum of its extension-header lengths. The unsigned 64-bit payload-length value underflows to a near-maximal integer, triggering an out-of-bounds read and oversized memcpy in the Windows kernel at DISPATCHLEVEL, resulting in a blue screen of death even on hosts with all ports blocked.

A local, non-privileged attacker can abuse a vulnerable IOCTL interface exposed by the OpenEDR 2.5.1.0 kernel driver to modify the DLL injection path used by the product. By redirecting this path to a user-writable location, an attacker can cause OpenEDR to load an attacker-controlled DLL into high-privilege processes. This results in arbitrary code execution with SYSTEM privileges, leading to full compromise of the affected system.

A local attacker can bypass OpenEDR's 2.5.1.0 self-defense mechanism by renaming a malicious executable to match a trusted process name (e.g., csrss.exe, edrsvc.exe, edrcon.exe). This allows unauthorized interaction with the OpenEDR kernel driver, granting access to privileged functionality such as configuration changes, process monitoring, and IOCTL communication that should be restricted to trusted components. While this issue alone does not directly grant SYSTEM privileges, it breaks OpenEDR's trust model and enables further exploitation leading to full local privilege escalation.