The tempnam function in ext/standard/file.c in PHP 5.2.11 and
earlier, and 5.3.x before 5.3.1, allows context-dependent attackers
to bypass safe_mode restrictions, and create files in group-writable
or world-writable directories, via the dir and prefix arguments.
PHP 5.2.5 does not enforce (a) open_basedir and (b)
safe_mode_exec_dir restrictions for certain functions, which might
allow local users to bypass intended access restrictions and call
programs outside of the intended directory via the (1) exec, (2)
system, (3) shell_exec, (4) passthru, or (5) popen functions,
possibly involving pathnames such as "C:" drive notation.
Thank you everyone, sorry about the delay.