KB5055561

Microsoft security update released 2025-04-08. Fixes 42 CVEs.

HighCISA KEVRansomware

Download KB5055561

Get the official update for KB5055561. The download and file size for each supported product are on the Microsoft Update Catalog page.

Microsoft Update Catalog: download KB5055561 Microsoft support article

Update summary

Released

2025-04-08

CVEs fixed

Max CVSS

8.8

Severity

High

Exploitation and severity

Fixes 42 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 8.8 (High). EPSS exploit probability up to 18%. One is linked to ransomware.

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

What to do

Treat as urgent: it is being exploited in the wild (CISA KEV), so patch ahead of items that are not. Senserva flags whether KB5055561 is missing on your devices.

Affected products

Windows 10 Version 1809 for 32-bit Systems
Windows 10 Version 1809 for x64-based Systems
Windows Server 2019

References

Microsoft support article Microsoft Security Update Guide

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