FreeBSD 14.4's Critical Kernel Flaw: One Syscall to Root Access

FreeBSD 14.4-RELEASE contains a critical kernel vulnerability in setcred(2) that enables any unprivileged user to escalate to root privileges with a single syscall, with no special exploit requirements. The flaw, caused by a sizeof type error, was silently fixed in the development branch but never backported to stable releases. This represents an urgent security risk for production FreeBSD systems, particularly those using the default ZFS filesystem.