Microsoft Security Bulletin MS13-103 – Important : Vulnerability in ASP.NET SignalR Could Allow Elevation of Privilege (2905244)

This security update resolves a privately reported vulnerability in ASP.NET SignalR. The vulnerability could allow elevation of privilege if an attacker reflects specially crafted JavaScript back to the browser of a targeted user.

This security update is rated Important for ASP.NET SignalR versions 1.1.0, 1.1.1, 1.1.2, 1.1.3 and 2.0.0, and all supported editions of Microsoft Visual Studio Team Foundation Server 2013. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by ensuring that ASP.NET SignalR properly encodes user input. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.


For customers who are developing web applications that use ASP.NET SignalR:
Customers who are developing web applications that use ASP.NET SignalR functionality are encouraged to follow the update guidance in the Security Update Deployment section of this bulletin for detailed instructions on how to update ASP.NET SignalR in their environments.

For customers running installations of Microsoft Visual Studio Team Foundation Server 2013:
For customers who have automatic updating enabled and who are running Microsoft Visual Studio Team Foundation Server 2013, the update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.

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.