Microsoft released KB4498523 and KB4502374 for Windows 10 1903. A few days ago, KB4497935 cumulative update came to the May 2019 update version raising its build to 18362.145. KB4498523 is a Service Stack Update (SSU) and KB4502374 is dynamic update. Both are distributed in the Release Preview Ring. A German blog deskmodder.de has updated this info and also offered links to third-party sites to download the patches. Release note for either of them is unavailable till now.
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KB4497936 Windows 10 1903 18362.113 Cumulative Update – 14 May 2019 KB4497093 for Windows 10 1903 Cumulative Update – 11 May, 2019 KB4497092 for Windows 10 1903 18362 (May 2019 Update)