An information disclosure vulnerability exists when Exchange allows creation of entities with Display Names having non-printable characters. An authenticated attacker could exploit this vulnerability by creating entities with invalid display names, which, when added to conversations, remain invisible. This security update addresses the issue by validating display names upon creation in Microsoft Exchange, and by rendering invalid display names correctly in Microsoft Outlook clients., aka 'Microsoft Exchange Information Disclosure Vulnerability'.

A denial of service vulnerability exists in Skype for Business, aka "Microsoft Skype for Business Denial of Service Vulnerability." This affects Office 365 ProPlus, Microsoft Office, Microsoft Lync, Skype.