CVE-2026-31431 (Copy Fail) is a critical privilege escalation flaw in the Linux kernel (versions 4.14 through current) that allows any unprivileged local user or container workload to achieve root access via a deterministic, artifact-free Python exploit. The flaw affects the vast majority of Linux-based cloud infrastructure, enterprise servers, and Kubernetes environments. A public 732-byte Python proof-of-concept with near-100% reliability is reported, and no CISA KEV listing exists yet — but the exploitation bar is extremely low pending vendor patch availability.