Security researchers have identified CVE-2026-31431, a minimal 732-byte Linux local privilege escalation vulnerability dubbed Copy Fail that affects major distributions since 2017. The exploit uses a single Python script to bypass file-integrity tools and cross container boundaries without relying on race conditions or distribution-specific offsets. Discovered by Xint Code, this straight-line attack works universally across Ubuntu, Amazon Linux, RHEL, and SUSE environments.