Nine-year-old Linux kernel flaw enables reliable local privilege escalation (CVE-2026-31431)

Security researchers disclosed CVE-2026-31431 "Copy Fail", a high-severity Linux kernel local privilege escalation that affects kernels released since 2017; a reliable proof-of-concept exploit is publicly available, it can be chained from remote footholds to achieve root and break container isolation, and administrators are urged to prioritize patching or apply temporary mitigations such as blocking AF_ALG sockets or blacklisting algif_aead.