These days, new Silverlight versions are typically released by Microsoft in connection with monthly Patch Tuesdays. That’s what happened with the latest version, 5.1.50901.0, which should have been installed with the other updates on Windows systems on October 11.

The new version fixes a single vulnerability, as documented in the associated security bulletin (MS16-120) and Knowledge Base article (KB3192884).

You can verify that you’re running the latest version of Silverlight by visiting the Get Microsoft Silverlight page.