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This page lists what has changed in the most recent definitions update for Windows Defender Antivirus and Microsoft Security Essentials.
If this page does not show change logs for the latest update (1.261.139.0), please try hitting refresh or let us know through the feedback link at the bottom of this page.
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The following tables list the new and updated definitions for the version you select here. You can choose from the 20 latest updates, and the most recent update is shown by default:
Definition available date: Jan 23,2018 11:01 AM UTC