FreeBSD Security Advisory – A programming error in the standard I/O library’s __sflush() function could erroneously adjust the buffered stream’s internal state even when no write actually occurred in the case when write(2) system call returns an error. The accounting mismatch would accumulate, if the caller does not check for stream status and will eventually lead to a heap buffer overflow. Such overflows may lead to data corruption or the execution of arbitrary code at the privilege level of the calling program.