Description of the security update for Outlook 2016: January 8, 2019

This security update resolves an information disclosure vulnerability that exists when Microsoft Outlook improperly handles certain types of messages. To learn more about the information disclosure vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2019-0559.

Note To apply this security update, you must have the release version of Outlook 2016 installed on the computer.

Be aware that the update in the Microsoft Download Center applies to the Microsoft Installer (.msi)-based edition of Office 2016. It doesn't apply to the Office 2016 Click-to-Run editions, such as Microsoft Office 365 Home (see Determining your Office version).

This security update contains the following improvements:

• Improves the stability of Microsoft Outlook 2016.

• Improves the Estonian translation of the Compact Navigation checkbox in the Navigation Options dialog box.

• Improves Dutch translations in the Outlook profile dialog box when you start Outlook 2016 in safe mode.

• Improves German translations of the text in the info bar that displays current voting results in an email message that has voting buttons.

• Adds support for the Do Not Forward policy for meetings so that the meetings can't be forwarded by attendees.

This security update contains fixes for the following nonsecurity issues:

• An email message that's saved as a plain text file will no longer have its message header field length vary based on the user's dots-per-inch (DPI) setting. This update fixes an issue with very narrow message header fields in high-DPI environments.

• After update KB 3118388 is applied, Office documents in Public Folders are unexpectedly opened in Protected View.

• A "Blocked external content" warning for Secure/Multipurpose Internet Mail Extensions (S/MIME) email messages that have no external content is displayed in Outlook 2016.

• When Outlook 2016 replies to a plain text email with an invalid code page, message headers in the body of a reply or forward email message are displayed incorrectly.

• When you access the Conversation History folder, Outlook 2016 hangs.

• When you forward an email message that contains inline attachments, the inline attachments may be attached as files in the new email message.

• When you open a custom form from the Organizational Forms Library, you experience a "Form load failed" error.

• This update fixes Outlook issues in Agave apps for 11 languages (Bulgarian, Dutch, Estonian, French, Greek, Hindi, Latvian, Lithuanian, Portuguese [Brazilian], Russian, and Spanish).

• Mail delivery rules stop working. When you try to open the Manage Rules and Alerts dialog box, you receive the following error message:

  The operation failed because of a registry or installation problem. Restart Outlook and try again. If the problem persists, reinstall.