Bugzilla 2.17.1 through 2.18rc2 and 2.19 from cvs, when using the insidergroup feature, does not sufficiently protect private attachments when there are changes to the metadata, such as filename, description, MIME type, or review flags, which allows remote authenticated users to obtain sensitive information when (1) viewing the bug activity log or (2) receiving bug change notification mails.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17842
https://bugzilla.mozilla.org/show_bug.cgi?id=253544
https://bugzilla.mozilla.org/show_bug.cgi?id=250605