KB5063899

Microsoft security update released 2025-08-12. Fixes 57 CVEs.

Critical

Download KB5063899

Get the official update for KB5063899. The download and file size for each supported product are on the Microsoft Update Catalog page.

Microsoft Update Catalog: download KB5063899 Microsoft support article

Update summary

Released

2025-08-12

CVEs fixed

Max CVSS

9.8

Severity

Critical

Exploitation and severity

Fixes 57 CVEs. Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 36%.

Among the top 25% of tracked Microsoft updates by EPSS exploit probability.

What to do

Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. Senserva flags whether KB5063899 is missing on your devices.

Affected products

Windows 10 Version 1809 for x64-based Systems
Windows Server 2019
Windows Server 2019 (Server Core installation)

References

Microsoft support article Microsoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.