The hook_comments API in Drupal 4.7.x before 4.7.8 and 5.x before 5.3 does not pass publication status, which might allow attackers to bypass access restrictions and trigger e-mail with unpublished comments from some modules, as demonstrated by (1) Organic groups and (2) Subscriptions.
https://www.redhat.com/archives/fedora-package-announce/2007-October/msg00328.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/37296
http://www.vupen.com/english/advisories/2007/3546
http://www.securityfocus.com/bid/26119
http://secunia.com/advisories/27352