The Debian php_crypt_revamped.patch patch for PHP 5.3.x, as used in the php5 package before 5.3.3-7+squeeze4 in Debian GNU/Linux squeeze, the php5 package before 5.3.2-1ubuntu4.17 in Ubuntu 10.04 LTS, and the php5 package before 5.3.5-1ubuntu7.10 in Ubuntu 11.04, does not properly handle an empty salt string, which might allow remote attackers to bypass authentication by leveraging an application that relies on the PHP crypt function to choose a salt for password hashing.