The ULE process scheduler in the FreeBSD kernel gives preference to "interactive" processes that perform voluntary sleeps, which allows local users to cause a denial of service (CPU consumption), as described in "Secretly Monopolizing the CPU Without Superuser Privileges."

The 4BSD process scheduler in the FreeBSD kernel performs scheduling based on CPU billing gathered from periodic process sampling ticks, which allows local users to cause a denial of service (CPU consumption) by performing voluntary nanosecond sleeps that result in the process not being active during a clock interrupt, as described in "Secretly Monopolizing the CPU Without Superuser Privileges."

The Linux kernel before 2.6.16.9 and the FreeBSD kernel, when running on AMD64 and other 7th and 8th generation AuthenticAMD processors, only save/restore the FOP, FIP, and FDP x87 registers in FXSAVE/FXRSTOR when an exception is pending, which allows one process to determine portions of the state of floating point instructions of other processes, which can be leveraged to obtain sensitive information such as cryptographic keys. NOTE: this is the documented behavior of AMD64 processors, but it is inconsistent with Intel processors in a security-relevant fashion that was not addressed by the kernels.