The comment module in Drupal 5.x before 5.23 and 6.x before 6.18 allows remote authenticated users with certain privileges to bypass intended access restrictions and reinstate removed comments via a crafted URL, related to an "unpublishing bypass" issue.
http://www.securityfocus.com/bid/42391
http://www.debian.org/security/2010/dsa-2113
http://marc.info/?l=oss-security&m=128440896914512&w=2