The Simplenews module 6.x-1.x before 6.x-1.4, 6.x-2.x before 6.x-2.0-alpha4, and 7.x-1.x before 7.x-1.0-rc1 for Drupal reveals the email addresses of new mailing list subscribers when confirmation is required, which allows remote attackers to obtain sensitive information via the confirmation page.
https://exchange.xforce.ibmcloud.com/vulnerabilities/76143
http://www.securityfocus.com/bid/53839
http://www.openwall.com/lists/oss-security/2012/06/14/3
http://drupalcode.org/project/simplenews.git/commitdiff/faec6a6
http://drupalcode.org/project/simplenews.git/commitdiff/6d5704c
http://drupalcode.org/project/simplenews.git/commitdiff/36352c1
http://drupal.org/node/1619848
http://drupal.org/node/1619820