FreeBSD Security Advisory - Three problems affect the /proc filesystem on FreeBSD. The first allows unprivileged local users can gain superuser privileges due to insufficient access control checks on the /proc//ctl files, which gives access to a process address space and perform various control operations on the process respectively. The second allows local users to deny service to a machine by mmap()ing a processes own /proc//mem file in the procfs filesystem. The third allows users with superuser privileges on the machine, including users with root privilege in a jail(8) virtual machine, to overflow a buffer in the kernel and bypass access control checks placed on the abilities of the superuser. This allows root users to break out of the jail environment, lower the securelevel, and load modules in kernels where module loading has been disabled.