Silverlight 5.1.50428.0 was released on June 21. Windows systems configured for auto-update should have received the update as soon as it became available. Without auto-update enabled, the new version should have been installed the first time Windows Update was run after June 21. The update is designated KB3162593.

Fortunately, the new version doesn’t fix any security issues. According to the release notes, it “Fixes the DateTime parsing for Norwegian and Serbian cultures.” So, not all that interesting, and certainly not an urgent update.