PHP Permissions Privileges and Access Controls Vulnerability - CVE-2009-3558
The posix_mkfifo function in ext/posix/posix.c in PHP before 5.2.12 and 5.3.x before 5.3.1 allows context-dependent attackers to bypass open_basedir restrictions and create FIFO files via the pathname and mode arguments as demonstrated by creating a .htaccess file.