Microsoft Outlook 2007 SP3, 2010 SP1 and SP2, 2013, and 2013 RT does not properly expand metadata contained in S/MIME certificates, which allows remote attackers to obtain sensitive network configuration and state information via a crafted certificate in an e-mail message, aka "S/MIME AIA Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19239
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-094