For those who have not seen it, this a recent security advisory letting users know to update to the latest stable FreeBSD.
A programming blunder involving integer signedness can be exploited by a logged-in user to crash a system. With the right parameters, you can trick the kernel into clearing too much of its heap memory with zeros via the sysarch system call, which will eventually lead to a kernel panic.II. Problem Description A special combination of sysarch(2) arguments, specify a request to uninstall a set of descriptors from the LDT. The start descriptor is cleared and the number of descriptors are provided. Due to invalid use of a signed intermediate value in the bounds checking during argument validity verification, unbound zero'ing of the process LDT and adjacent memory can be initiated from usermode. III. Impact This vulnerability could cause the kernel to panic. In addition it is possible to perform a local Denial of Service against the system by unprivileged processes.
Original article: http://www.theregister.co.uk/2016/03/18/freebsd_bug_patched/
Security Advisory: https://www.freebsd.org/security/advisories/FreeBSD-SA-16:15.sysarch.asc