IBM has discovered and (on Friday, December 14, 2018) released a patch for a security vulnerability in NSD (Notes System Diagnostics) for Windows. So now is a really good time to upgrade your Windows-based Domino servers to 9.0.1FP10IF5 and your Windows-based Notes clients to version 9.0.1FP10IF6. (Or you could upgrade them to version 10.)
Here's the Technote with the details.