Software bug
Some bugs affect hardware (the physical parts of a computer) instead of software. For example, running the instruction lock cmpxchg8b eax on old Pentium processors would cause the processor to stop working until rebooted. Since hardware bugs are physical design flaws, they can not be corrected with a software update, although it may be possible to work around (hide) the bug with a software update, for example, by checking for the conditions that cause the bug or by rearranging data in a way that prevents the bug from occurring.