A short time ago a "local root" exploit was posted to the full-disclosure
mailing list; as the name suggests, this allows a local user to execute
arbitrary code as root.
Normally it is the policy of the FreeBSD Security Team to not publicly
discuss security issues until an advisory is ready, but in this case
since exploit code is already widely available I want to make a patch
available ASAP. Due to the short timeline, it is possible that this
patch will not be the final version which is provided when an advisory
is sent out; it is even possible (although highly doubtful) that this
patch does not fully fix the issue or introduces new issues -- in short,
use at your own risk (even more than usual).