FreeBSD Security Advisory FreeBSD-SA-04:02.shmat - A programming error in the shmat(2) system call can result in a shared memory segment's reference count being erroneously incremented. It may be possible to cause a shared memory segment to reference unallocated kernel memory, but remain valid. This could allow a local attacker to gain read or write access to a portion of kernel memory, resulting in sensitive information disclosure, bypass of access control mechanisms, or privilege escalation.