KB5074109: Windows 10 Version 1809 for 32-bit Sys Security Update (January 2026)

Download KB5074109

Get the official update for KB5074109. The download and file size for each supported product are on the Microsoft Update Catalog page.

Update summary

Senserva AI Opinion for KB5074109

KB5074109 is a large January 2026 rollup patching 86 CVEs across Windows 11 25H2 and the older Windows 10 1809, with a top rating of Critical (CVSS 9.8) and a 73% EPSS score signaling real near-term exploitation probability. At least one of its CVEs is already listed in the CISA KEV catalog, meaning it is being exploited in the wild, though none are currently tied to ransomware. The mix of a modern (25H2) and legacy (1809) build in one KB means both current and lagging fleets are exposed.

Do this: Prioritize deploying KB5074109 immediately to any Windows 10 1809 and Windows 11 25H2 systems, starting with internet-facing and unpatched hosts given the confirmed KEV entry.

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

Senserva AI Opinion and rich prompt for KB5074109

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

Full tracking and change history for KB5074109

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.

Exploitation and severity

Fixes 86 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 73%.

Among the top 10% 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 KB5074109 is missing on your devices.

Check if KB5074109 is installed

Copy-paste PowerShell: one machine, or your whole fleet in one pass. No output means the update is not installed.

Get-HotFix covers Windows updates. Office, SharePoint, and Exchange server updates show under installed updates in Programs and Features, or check the Update Catalog history.

Writing about KB5074109? Cite this page

Copy-paste for a blog post, forum answer, or internal doc. The link always carries the current risk data.

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.

Affected products

• Windows 10 Version 1809 for 32-bit Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems

Also released in January 2026

The highest-risk updates from the same release:

The full month, summarized: Microsoft Patch Tuesday.

How to install KB5074109

Any of these paths delivers KB5074109; most organizations already have one of the first three running:

• Intune update rings (Windows Update for Business): the update flows on each ring's deferral schedule. For this update, consider an expedite policy: it bypasses deferrals for exactly this fix-now case.
• Windows Autopatch: rings, rollout, and pause or rollback are managed for you; exploited updates can be expedited.
• WSUS / Configuration Manager: approve KB5074109 for your device groups and set a deadline (deadline, not just approval, for an exploited fix).
• Manual: download from the Update Catalog above and install; fine for a handful of machines, unmanageable at any real scale.

After the rollout, verify rather than assume: update compliance reporting in Intune or Autopatch shows which devices actually installed it, and Siemserva reads Intune, Defender, Autopatch, and Azure Update Manager together to show the devices still missing KB5074109, ranked by exploitation.

Common questions about KB5074109

Is KB5074109 urgent?

Yes. KB5074109 fixes at least one vulnerability in the CISA Known Exploited Vulnerabilities catalog, meaning attackers are using it in the wild. Deploy it first.

How do I download KB5074109?

From the Microsoft Update Catalog (linked on this page), or let Intune, Windows Update for Business, Windows Autopatch, or WSUS deliver it. The catalog page lists the download for each supported product.

How do I deploy KB5074109 with Intune?

Assign a Windows Update ring (quality update policy) to the device groups and the update flows on the ring's deferral schedule. Because KB5074109 fixes an actively exploited CVE, an Intune expedite policy is the right tool: it bypasses configured deferrals and pushes the update as soon as devices check in. Verify the rollout with update compliance reporting rather than assuming delivery.

Can I ask my own AI about KB5074109?

Yes. This page includes a free, ready-to-paste AI prompt containing KB5074109's key facts: severity, CVE count, exploitation status, and the download link. Copy it into Claude, ChatGPT, or Copilot for a rollout plan; the data is refreshed three times a day (5 AM, 12:30 PM, and 7 PM US Central).

Authoritative references