CVE-2026-64600: RefluXFS Linux Kernel Flaw Can Lead to Root Privilege Escalation

CVE-2026-64600 (RefluXFS) is a Linux kernel vulnerability in the XFS reflink copy-on-write path that allows an unprivileged local attacker to exploit a race between concurrent O_DIRECT writes to overwrite readable files and achieve persistent root privilege; exploitation was demonstrated against default RHEL 10.2. The issue affects kernels 4.11+ on XFS volumes with reflink enabled, leaves minimal forensic evidence, and is best mitigated by applying vendor kernel patches and rebooting to the fixed kernel.