Common Vulnerabilities and Exposures assigned an identifier CVE-2007-5424 to the following vulnerability: The disable_functions feature in PHP 4 and 5 allows attackers to bypass intended restrictions by using an alias, as demonstrated by using ini_alter when ini_set is disabled. References: http://www.securityfocus.com/archive/1/archive/1/482006/100/0/threaded http://securityvulns.com/news/PHP/alias-pb.html http://securityvulns.ru/Sdocument67.html
Apart from that documentation doesn't say the function should disable the function aliases, so the behavior of disable_functions is correct and this is not even a functional bug.
The PHP "disable_functions" configuration option is intended to prevent an interpreted script from calling specific functions. But the PHP interpreter does not offer a "sandboxed" security layer (as found in, say, a JVM) with which to reliably implement these features, so they cannot be relied upon as a security feature. Any bug in PHP (or any extension) which allows a script to corrupt memory or cause the interpreter to crash may allow the script to bypass disable_functions. Similarly, any feature of a bundled (or third-party) extension which allows the script to open arbitrary files, or execute arbitrary commands, may allow the script to bypass disable_functions restrictions. For these reasons, bugs in the PHP interpreter or extensions which allow scripts to bypass these options, will not be treated as security-sensitive. See also http://www.php.net/security-note.php for the similar position taken by the PHP project.