An information disclosure vulnerability exists when attaching files to Outlook messages. This vulnerability could potentially allow users to share attached files such that they are accessible by anonymous users where they should be restricted to specific users.
To exploit this vulnerability, an attacker would have to attach a file as a link to an email. The email could then be shared with individuals that should not have access to the files, ignoring the default organizational setting.
The security update addresses the vulnerability by correcting how Outlook handles file attachment links.