New "Bad Epoll" Linux Kernel Flaw Lets Unprivileged Users Gain Root, Hits Android
Jul 03, 2026
Linux / Android
A newly disclosed Linux kernel flaw called Bad Epoll (CVE-2026-46242) lets an ordinary user with no special access take full control of a machine as root. It affects Linux desktops, servers, and Android, and a fix is out. Bad Epoll sits in the same small stretch of kernel code where Anthropic's most powerful AI model, Mythos , recently found a different bug. The AI caught one flaw and missed this one. A researcher, Jaeyoung Chung, found it and built a working attack. How the Bug Works Epoll is a standard Linux feature that lets a program watch many files or network connections at once. Servers, network services, and web browsers all lean on it. You cannot simply switch it off. Bad Epoll is a "use-after-free" bug. Two parts of the kernel try to clean up the same internal object at the same time. One frees the memory while the other is still writing into it. That brief collision lets an attacker corrupt kernel memory, then climb from a normal account up to root...
