Linux Kernel Flaw Enables Root Access On Servers and Android Devices

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A newly disclosed Linux kernel vulnerability is drawing widespread attention after researchers demonstrated that it can reliably elevate an unprivileged user to full root privileges on affected Linux systems and Android devices. Tracked as CVE-2026-46242 and nicknamed “Bad Epoll,” the flaw affects one of Linux’s most fundamental kernel subsystems, making it particularly difficult to mitigate without installing security updates.

Unlike many recent Linux privilege escalation vulnerabilities that rely on optional kernel modules or niche configurations, Bad Epoll resides within the kernel’s epoll implementation—a high-performance event notification mechanism used extensively by web servers, databases, browsers, cloud services, networking software and Android itself. Because epoll is integral to normal operating system functionality, administrators have no practical workaround other than applying patched kernels supplied by Linux distributions and Android vendors.

The vulnerability was discovered by security researcher Jaeyoung Chung, who submitted a working exploit through Google’s kernelCTF bug bounty program. The exploit demonstrates that even an ordinary local user account can be transformed into a fully privileged root session, achieving approximately 99% reliability on tested systems despite exploiting an exceptionally small race window.

A Flaw Hidden Inside One of Linux’s Most Important Components

The affected subsystem, epoll, has existed for years as one of Linux’s most efficient methods for monitoring thousands of simultaneous file descriptors without consuming excessive CPU resources.

Nearly every modern Linux server depends on…

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