Integer overflow in the fcount counter in FreeBSD before 4.2 through 5.0 allows local users to cause a denial of service (crash) and possibly execute arbitrary code via multiple calls to (1) fpathconf and (2) lseek, which do not properly decrement fcount through a call to fdrop.

Race condition in exec in OpenBSD 4.0 and earlier, NetBSD 1.5.2 and earlier, and FreeBSD 4.4 and earlier allows local users to gain privileges by attaching a debugger to a process before the kernel has determined that the process is setuid or setgid.

The kernel in FreeBSD 3.2 follows symbolic links when it creates core dump files, which allows local attackers to modify arbitrary files.

FreeBSD 5.x, 4.x, and 3.x allows local users to cause a denial of service by executing a program with a malformed ELF image header.

The undocumented semconfig system call in BSD freezes the state of semaphores, which allows local users to cause a denial of service of the semaphore system by using the semconfig call.

FreeBSD VFS cache (vfscache) allows local users to cause a denial of service by opening a large number of files.

FreeBSD, NetBSD, and OpenBSD allow an attacker to cause a denial of service by creating a large number of socket pairs using the socketpair function, setting a large buffer size via setsockopt, then writing large buffers.

FreeBSD 3.2 and possibly other versions allows a local user to cause a denial of service (panic) with a large number accesses of an NFS v3 mounted directory from a large number of processes.

OpenBSD, BSDI, and other Unix operating systems allow users to set chflags and fchflags on character and block devices.