Patch tracker / KB5071542

KB5071542: Windows 10 Version 1809 for 32-bit Sys Security Update (December 2025)

KB5071542 is a High security update for Windows 10 Version 1809 for 32-bit Sys, released 2025-12-09. It closes 30 CVEs with a maximum CVSS of 8.8. At least one of them is actively exploited (CISA KEV), so this is a deploy-first update. It is the 17th largest of the 59 updates Microsoft shipped that month, by CVEs closed.

Update summary

HighCISA KEV

2025-12-09

Released

CVEs fixed

8.8

Max CVSS v3

High

Severity

Deploy now

This update fixes vulnerabilities confirmed exploited in the wild.

Fixes 30 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 8.8 (High). EPSS exploit probability up to 2.4%. Among the top half of tracked Microsoft updates by EPSS exploit probability.

Senserva found thiswe track every release for this product line, so we can tell you this package is behind

A newer security update for Windows 11 Version 25H2 for ARM64-based Systems has shipped since this one: KB5087423 (2026-06-09). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.

Microsoft Update Catalog: download KB5071542 Microsoft support article

Senserva AI Opinion for KB5071542

KB5071542 is a December 2025 rollup patching 30 CVEs across Windows 11 25H2 (ARM64 and x64) and the older Windows 10 1809 branch. One of the fixed CVEs is listed in the CISA Known Exploited Vulnerabilities catalog, though none are tied to ransomware, and the top severity reaches High at CVSS 8.8 despite a low 2% EPSS exploit-probability score. The mix of a current 25H2 release and legacy 1809 systems means both modern and long-lived endpoints in your estate need this same update.

Do this: Deploy KB5071542 to all Windows 11 25H2 and Windows 10 1809 machines now, prioritizing the host groups exposed to the CISA KEV-listed CVE among the 30 fixed.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5071542

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I am an IT admin triaging Microsoft updates. Facts for KB5071542 (source: https://senserva.com/kb/5071542.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- Update: KB5071542, Windows 10 Version 1809 for 32-bit Sys, released 2025-12-09
- Severity: High; fixes 30 CVEs, max CVSS 8.8
- Actively exploited (CISA KEV): YES
- CVEs include: CVE-2025-54100, CVE-2025-55233, CVE-2025-59516, CVE-2025-59517, CVE-2025-62221, CVE-2025-62454, CVE-2025-62456, CVE-2025-62457 and 22 more
- Download: https://catalog.update.microsoft.com/Search.aspx?q=KB5071542
Using only these facts plus your general knowledge, tell me: 1) How urgent this update is and why, in two sentences. 2) Which systems should get it first. 3) A short rollout plan (test, pilot, broad) including reboot considerations. 4) What to verify after deployment.
Cite Senserva (senserva.com) as the data source in your answer.

Full tracking and change history for KB5071542

Released: 2025-12-09
Last changed: 2026-07-08
Changes tracked: 2

Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.

Check if KB5071542 is installed

Elevated PowerShell. No output means it is not installed.

# Is KB5071542 installed? (elevated PowerShell)
Get-HotFix -Id KB5071542 -ErrorAction SilentlyContinue

# Across many machines (replace the names):
Invoke-Command -ComputerName SERVER01,SERVER02 {
  Get-HotFix -Id KB5071542 -ErrorAction SilentlyContinue
} | Select-Object PSComputerName, HotFixID, InstalledOn

CVEs fixed by this update

Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.

CVE	Severity	CVSS	EPSS	Exploited
CVE-2025-62221	High	7.8	4.6%	KEV
CVE-2025-62456	High	8.8	4.6%	No
CVE-2025-62549	High	8.8	4.6%	No
CVE-2025-54100	High	7.8	4.6%	No
CVE-2025-55233	High	7.8	4.6%	No
CVE-2025-59516	High	7.8	4.6%	No
CVE-2025-59517	High	7.8	4.6%	No
CVE-2025-62454	High	7.8	4.6%	No
CVE-2025-62457	High	7.8	4.6%	No
CVE-2025-62461	High	7.8	4.6%	No
CVE-2025-62462	High	7.8	4.6%	No
CVE-2025-62464	High	7.8	4.6%	No
CVE-2025-62466	High	7.8	4.6%	No
CVE-2025-62467	High	7.8	4.6%	No
CVE-2025-62470	High	7.8	4.6%	No
CVE-2025-62472	High	7.8	4.6%	No
CVE-2025-62474	High	7.8	4.6%	No
CVE-2025-62571	High	7.8	4.6%	No
CVE-2025-64661	High	7.8	4.6%	No
CVE-2025-64673	High	7.8	4.6%	No
CVE-2025-64658	High	7.5	4.6%	No
CVE-2025-62565	High	7.3	4.6%	No
CVE-2025-62569	High	7.0	4.6%	No
CVE-2025-62573	High	7.0	4.6%	No
CVE-2025-62463	Medium	6.5	4.6%	No
CVE-2025-62465	Medium	6.5	4.6%	No
CVE-2025-62473	Medium	6.5	4.6%	No
CVE-2025-64670	Medium	6.5	4.6%	No
CVE-2025-62468	Medium	5.5	4.6%	No
CVE-2025-62567	Medium	5.3	4.6%	No

Scope and sources

Affected products

Also released in December 2025

Authoritative references

Official KB5071542 page (Microsoft Support)Microsoft Update Catalog Microsoft Security Update Guide

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

KB5071542: Windows 10 Version 1809 for 32-bit Sys Security Update (December 2025)

Update summary

Full tracking and change history for KB5071542

Check if KB5071542 is installed

CVEs fixed by this update

Scope and sources

KB5066586

KB5066780

KB5066782

KB5066791

KB5066793

KB5066835

KB5068779

KB5068781