A kernel flaw is a weakness in the core code of an operating system, the part that manages memory, processes, devices, and security boundaries. Because the kernel runs with the highest level of privilege, a single flaw can affect many users, applications, and even whole fleets of machines using the same platform.
In cyber security, kernel flaws matter because attackers can use them to escalate privileges, bypass protections, crash systems, or sometimes execute code with near-total control. Defenders treat them as high-priority issues: they review vendor advisories, patch quickly, and monitor for signs of exploitation. In real attacks, kernel flaws often appear in chains, where malware or a foothold on a host uses the flaw to gain full system access.