As per their usual schedule, Microsoft has released December 2018 patch updates for Windows 10 Mobile. The KB4478936 cumulative update brings fixes as well as security patches to make sure Windows 10 Mobile is secure.
You can head below to take a look at the official changelog for the update. The new cumulative update bumps the OS to v15254.544 as well.
- Resolves an issue that may prevent the Search Bar from using Windows Media Player when playing specific files. This problem does not affect normal playback.
- Security updates to Microsoft Scripting Engine, Internet Explorer, Windows platform and app framework, Microsoft graphic component, Windows graphics, Microsoft Edge, Windows kernel, Windows storage and file system, Windows authentication and Windows wireless network.
The update will be downloaded and installed automatically. However, you could head to Settings>Update and Security>Windows Update and tap on Check for Updates to download and install updates manually.