Bugzilla 2.18rc1 through 2.18.3, 2.19 through 2.20rc2, and 2.21 allows remote attackers to obtain sensitive information such as the list of installed products via the config.cgi file, which is accessible even when the requirelogin parameter is set.

Bugzilla 2.19.1 through 2.20rc2 and 2.21, with user matching turned on in substring mode, allows attackers to list all users whose names match an arbitrary substring, even when the usevisibilitygroups parameter is set.