New Linux 'Copy Fail' Vulnerability Enables Root Access on Major Distributions

**CVE-2026-31431 ("Copy Fail") — Linux local privilege escalation (CVSS 7.8):** Researchers disclosed a logic flaw in the kernel algif_aead crypto module introduced in 2017 that lets an unprivileged local user write four controlled bytes into the page cache of readable files, enabling reliable, tiny, cross-distribution exploitation (including cross-container) to modify setuid binaries and escalate to root; vendors have published advisories and patches.