Nine-Year-Old Zero-Day Flaw in Linux Kernel Discovered by AI-Equipped Security Researcher

**Copy Fail (CVE-2026-31431)** — A logic bug in the Linux kernel's authenticated encryption template introduced in 2017 allows an unprivileged local user with physical access to trigger a deterministic four‑byte write into the page cache of any readable file, enabling local privilege escalation to root across affected kernels; a proof‑of‑concept exploit has been published, the issue is rated CVSS 7.8, and distributions have released patches that revert the problematic AEAD optimization (update to include commit a664bf3d603d).