PHP before 5.4.41, 5.5.x before 5.5.25, and 5.6.x before 5.6.9 truncates a pathname upon encountering a \x00 character in certain situations, which allows remote attackers to bypass intended extension restrictions and access files or directories with unexpected names via a crafted argument to (1) set_include_path, (2) tempnam, (3) rmdir, or (4) readlink.  NOTE: this vulnerability exists because of an incomplete fix for CVE-2006-7243.