Version 3.5.1 (latest) of popular blogging engine WordPress suffers from remote denial of service vulnerability. The bug exists in encryption module (class-phpass.php). The exploitation of this vulnerability is possible only when at least one post is protected by a password.
Time frames: 31.05.2013 WordPress security team has been informed about the vulnerability (no response). 07.06.2013 The vulnerability has been released to the public.
More information (including proof of concept): https://vndh.net/note:wordpress-351-denial-service
A way out (before official WordPress update) to secure existing installations is to apply the following patch:
--- wp-includes/class-phpass.php +++ wp-includes/class-phpass.php @@ -120,7 +120,7 @@ return $output;
$count_log2 = strpos($this->itoa64, $setting);
$count = 1 << $count_log2;