The (1) execve and (2) fexecve system calls in the FreeBSD kernel 8.4 before p11, 9.1 before p14, 9.2 before p7, and 10.0 before p4 destroys the virtual memory address space and mappings for a process before all threads have terminated, which allows local users to cause a denial of service (triple-fault and system reboot) via a crafted system call, which triggers an invalid page table pointer dereference.