Patch tracker / KB5073450

KB5073450: Windows 10 Version 1809 for 32-bit Sys Security Update (January 2026)

KB5073450 is a Critical security update for Windows 10 Version 1809 for 32-bit Sys, released 2026-01-13. It closes 80 CVEs with a maximum CVSS of 9.8. At least one of them is actively exploited (CISA KEV), so this is a deploy-first update. Get it from the Microsoft Update Catalog below, and see where it sits against the rest of the month on the patch tracker.

CriticalCISA KEV

Update summary

Released

2026-01-13

CVEs fixed

Max CVSS

9.8

Severity

Critical

Deploy now

This update fixes vulnerabilities confirmed exploited in the wild.

Microsoft Update Catalog: download KB5073450 Microsoft support article

A newer security update for Windows 11 Version 25H2 for x64-based Systems has shipped since this one: KB5087423 (2026-06-09). For cumulative update families the newer package includes these fixes.

Take a look before you deploy: this update has 3 known issues

Microsoft's own support article for KB5073450 documents the following, as of 2026-08-04.

Windows Server Update Services (WSUS) does not display error details
Connection and authentication failures in Azure Virtual Desktop and Windows 365
Apps might become unresponsive when saving files to cloud-based storage

Read the full known issues · Microsoft's article

New to these terms? How the Microsoft patching tools fit together, this month's Patch Tuesday summary, and every update ranked by real-world risk.

Senserva AI Opinion for KB5073450

KB5073450 is a large January 2026 rollup fixing 80 CVEs across Windows 11 25H2 (x64 and ARM64) and Windows 10 1809, topped by a Critical flaw at CVSS 9.8 with EPSS at 74 percent. At least one of these CVEs is on the CISA KEV list, meaning it is confirmed exploited in the wild, though none are currently tied to ransomware. The mix of a very high severity remote flaw plus known active exploitation makes this a priority regardless of edition.

Do this: Deploy KB5073450 to your Windows 11 25H2 and Windows 10 1809 fleet now, prioritizing internet-facing and remotely accessible systems given the KEV-listed exploited CVE.

AI-generated from public data, 2026-07-25. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5073450

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 KB5073450 (source: https://senserva.com/kb/5073450.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- Update: KB5073450, Windows 10 Version 1809 for 32-bit Sys, released 2026-01-13
- Severity: Critical; fixes 80 CVEs, max CVSS 9.8
- Actively exploited (CISA KEV): YES
- CVEs include: CVE-2023-31096, CVE-2024-55414, CVE-2025-6965, CVE-2026-0386, CVE-2026-20804, CVE-2026-20805, CVE-2026-20808, CVE-2026-20809 and 72 more
- Download: https://catalog.update.microsoft.com/Search.aspx?q=KB5073450
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 KB5073450

Released

2026-01-13

Last changed

2026-08-04

Changes tracked

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 80 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 75%.

Among the top 25% 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 KB5073450 is missing on your devices.

Check if KB5073450 is installed

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

# Is KB5073450 installed? (elevated PowerShell)
Get-HotFix -Id KB5073450 -ErrorAction SilentlyContinue

# Across many machines (replace the names):
Invoke-Command -ComputerName SERVER01,SERVER02 {
  Get-HotFix -Id KB5073450 -ErrorAction SilentlyContinue
} | Select-Object PSComputerName, HotFixID, InstalledOn

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.

Known issues, from Microsoft

Quoted from Microsoft's support article for KB5073450 (checked 2026-08-04). Verify against the article before acting.

Windows Server Update Services (WSUS) does not display error details

After installing KB5070879 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287 .

Connection and authentication failures in Azure Virtual Desktop and Windows 365

Symptoms

After installing the January 2026 security update ( KB5073450 ), released on January 13, 2026, credential prompt failures occured during Remote Desktop connections using the Windows App on Windows client devices, impacting Azure Virtual Desktop and Windows 365. The issue affects Windows App on specific Windows builds, causing sign-in failures.

Workaround

This issue is addressed in KB5077792 .

Apps might become unresponsive when saving files to cloud-based storage

Symptom

After installing this update, some applications may become unresponsive or encounter unexpected errors when opening files from or saving files to cloud-based storage, such as OneDrive or Dropbox. In certain Outlook configurations that store PST files on OneDrive, Outlook may hang and fail to reopen unless the process is terminated or the system is restarted. Users may also see missing sent Items or previously downloaded emails being re‑downloaded.

Workaround

This issue is addressed in ...

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-2026-20805	Critical	9.8	75%	KEV
CVE-2023-31096	Critical	9.8	75%	No
CVE-2024-55414	Critical	9.8	75%	No
CVE-2025-6965	Critical	9.8	75%	No
CVE-2026-0386	Critical	9.8	75%	No
CVE-2026-20804	Critical	9.8	75%	No
CVE-2026-20808	Critical	9.8	75%	No
CVE-2026-20809	Critical	9.8	75%	No
CVE-2026-20811	Critical	9.8	75%	No
CVE-2026-20812	Critical	9.8	75%	No
CVE-2026-20814	Critical	9.8	75%	No
CVE-2026-20816	Critical	9.8	75%	No
CVE-2026-20817	Critical	9.8	75%	No
CVE-2026-20818	Critical	9.8	75%	No
CVE-2026-20820	Critical	9.8	75%	No
CVE-2026-20821	Critical	9.8	75%	No
CVE-2026-20822	Critical	9.8	75%	No
CVE-2026-20823	Critical	9.8	75%	No
CVE-2026-20824	Critical	9.8	75%	No
CVE-2026-20825	Critical	9.8	75%	No
CVE-2026-20826	Critical	9.8	75%	No
CVE-2026-20827	Critical	9.8	75%	No
CVE-2026-20828	Critical	9.8	75%	No
CVE-2026-20829	Critical	9.8	75%	No
CVE-2026-20831	Critical	9.8	75%	No
CVE-2026-20832	Critical	9.8	75%	No
CVE-2026-20833	Critical	9.8	75%	No
CVE-2026-20834	Critical	9.8	75%	No
CVE-2026-20835	Critical	9.8	75%	No
CVE-2026-20836	Critical	9.8	75%	No
CVE-2026-20837	Critical	9.8	75%	No
CVE-2026-20838	Critical	9.8	75%	No
CVE-2026-20839	Critical	9.8	75%	No
CVE-2026-20840	Critical	9.8	75%	No
CVE-2026-20842	Critical	9.8	75%	No
CVE-2026-20843	Critical	9.8	75%	No
CVE-2026-20844	Critical	9.8	75%	No
CVE-2026-20847	Critical	9.8	75%	No
CVE-2026-20848	Critical	9.8	75%	No
CVE-2026-20849	Critical	9.8	75%	No
CVE-2026-20852	Critical	9.8	75%	No
CVE-2026-20856	Critical	9.8	75%	No
CVE-2026-20857	Critical	9.8	75%	No
CVE-2026-20858	Critical	9.8	75%	No
CVE-2026-20860	Critical	9.8	75%	No
CVE-2026-20861	Critical	9.8	75%	No
CVE-2026-20862	Critical	9.8	75%	No
CVE-2026-20863	Critical	9.8	75%	No
CVE-2026-20864	Critical	9.8	75%	No
CVE-2026-20865	Critical	9.8	75%	No
CVE-2026-20866	Critical	9.8	75%	No
CVE-2026-20867	Critical	9.8	75%	No
CVE-2026-20868	Critical	9.8	75%	No
CVE-2026-20869	Critical	9.8	75%	No
CVE-2026-20871	Critical	9.8	75%	No
CVE-2026-20872	Critical	9.8	75%	No
CVE-2026-20873	Critical	9.8	75%	No
CVE-2026-20874	Critical	9.8	75%	No
CVE-2026-20875	Critical	9.8	75%	No
CVE-2026-20876	Critical	9.8	75%	No
CVE-2026-20877	Critical	9.8	75%	No
CVE-2026-20918	Critical	9.8	75%	No
CVE-2026-20919	Critical	9.8	75%	No
CVE-2026-20920	Critical	9.8	75%	No
CVE-2026-20921	Critical	9.8	75%	No
CVE-2026-20922	Critical	9.8	75%	No
CVE-2026-20923	Critical	9.8	75%	No
CVE-2026-20924	Critical	9.8	75%	No
CVE-2026-20925	Critical	9.8	75%	No
CVE-2026-20926	Critical	9.8	75%	No
CVE-2026-20927	Critical	9.8	75%	No
CVE-2026-20929	Critical	9.8	75%	No
CVE-2026-20931	Critical	9.8	75%	No
CVE-2026-20932	Critical	9.8	75%	No
CVE-2026-20934	Critical	9.8	75%	No
CVE-2026-20936	Critical	9.8	75%	No
CVE-2026-20937	Critical	9.8	75%	No
CVE-2026-20939	Critical	9.8	75%	No
CVE-2026-20962	Critical	9.8	75%	No
CVE-2026-21265	Critical	9.8	75%	No

Affected products

Also released in January 2026

The highest-risk updates from the same release:

KB5002822 KB5002825 KB5002828 KB5073379 KB5073455 KB5073457 KB5073722 KB5073723

The full month, summarized: Microsoft Patch Tuesday.

Authoritative references

Official KB5073450 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.