This security update resolves one publicly disclosed vulnerability and three privately reported vulnerabilities in Microsoft Lync. The most severe vulnerabilities could allow remote code execution if a user views shared content that contains specially crafted TrueType fonts.

This security update is rated Important for Microsoft Lync 2010, Microsoft Lync 2010 Attendee, Microsoft Lync 2010 Attendant (32-bit), and Microsoft Lync 2010 Attendant (64-bit). For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerabilities by correcting how specially crafted True Type Font files are handled, correcting the manner in which Microsoft Lync loads external libraries, and modifying the way that SafeHTML function sanitizes HTML content. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. Customers can configure automatic updating to check online for updates from Microsoft Update by using the Microsoft Update service. Customers who have automatic updating enabled and configured to check online for updates from Microsoft Update typically will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates from Microsoft Update and install this update manually. For information about specific configuration options in automatic updating in supported editions of Windows XP and Windows Server 2003, see Microsoft Knowledge Base Article 294871. For information about automatic updating in supported editions of Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, see Understanding Windows automatic updating.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update at the earliest opportunity using update management software, or by checking for updates using the Microsoft Update service.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Known Issues. Microsoft Knowledge Base Article 2707956 documents the currently known issues that customers may experience when installing this security update. The article also documents recommended solutions for these issues.

Reference: http://technet.microsoft.com/en-us/security/bulletin/ms12-039