The CDN module 6.x-2.2 and 7.x-2.2 for Drupal, when running in Origin Pull mode with the "Far Future expiration" option enabled, allows remote attackers to read arbitrary PHP files via unspecified vectors, as demonstrated by reading settings.php.
https://drupal.org/node/1441502
http://www.openwall.com/lists/oss-security/2012/04/07/1
http://secunia.com/advisories/48032
http://drupalcode.org/project/cdn.git/commitdiff/eca85e6
http://drupalcode.org/project/cdn.git/commitdiff/cd2a5ff