Description of problem:
PHP 4.x and 5.x before 5.2.1, when running on multi-threaded systems, does not
ensure thread safety for libc crypt function calls using protection schemes such
as a mutex, which creates race conditions that allow remote attackers to
overwrite internal program memory and gain system access.
PHP is not built or supported in a multi-threaded environment in the packages
distributed in Red Hat Enterprise Linux.