RefluXFS Linux Kernel Vulnerability Lets Attackers Gain Root Access

Qualys TRU disclosed RefluXFS (CVE-2026-64600), a race condition in the XFS reflink copy-on-write path that allows unprivileged local users to perform concurrent O_DIRECT writes to corrupt on-disk blocks and silently escalate to root, bypassing SELinux and container isolation; the bug affects Linux kernels since 4.11 on reflink-enabled XFS volumes, impacts millions of systems, leaves no kernel log artifacts, and requires immediate patching and reboot as there is currently no reliable workaround.