PHP 5.2.0 and 4.4 allows local users to bypass safe_mode and open_basedir restrictions via a malicious path and a null byte before a ";" in a session_save_path argument, followed by an allowed path, which causes a parsing inconsistency in which PHP validates the allowed path but sets session.save_path to the malicious path.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.