Template.pm in Bugzilla 3.3.2 through 3.4.3 and 3.5 through 3.5.1 allows remote attackers to discover the alias of a private bug by reading the (1) Depends On or (2) Blocks field of a related bug.
https://exchange.xforce.ibmcloud.com/vulnerabilities/54332
https://bugzilla.mozilla.org/show_bug.cgi?id=529416
http://www.vupen.com/english/advisories/2009/3288
http://www.securityfocus.com/bid/37062
http://www.bugzilla.org/security/3.4.3/