KB5073455: Windows 10 Version 1809 for 32-bit Sys Security Update (January 2026)

Update summary

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

Microsoft's own support article for KB5073455 documents the following, as of 2026-08-04.

• Connection and authentication failures in Azure Virtual Desktop and Windows 365
• Secure Launch-capable devices might fail to shut down or hibernate
• Apps might become unresponsive when saving files to cloud-based storage

Read the full known issues  ·  Microsoft's article

Senserva AI Opinion for KB5073455

KB5073455 patches 80 CVEs across Windows 11 25H2 (x64 and ARM64) and Windows 10 1809, topping out at Critical severity with a CVSS 9.8 flaw. One of these CVEs is already in the CISA KEV catalog, meaning it is confirmed exploited in the wild, and the highest EPSS of 74 percent signals near-term exploitation likelihood, though none are currently tied to ransomware campaigns.

Do this: Deploy KB5073455 to all Windows 11 25H2 and Windows 10 1809 systems this cycle, prioritizing internet-facing hosts because of the KEV-listed CVE.

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

Full tracking and change history for KB5073455

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 KB5073455 is missing on your devices.

Check if KB5073455 is installed

Copy-paste PowerShell: one machine, or your whole estate 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.

Known issues, from Microsoft

Quoted from Microsoft's support article for KB5073455 (checked 2026-08-04). Verify against the article before acting.

Connection and authentication failures in Azure Virtual Desktop and Windows 365

Symptoms

After installing the January 2026 security update ( KB5073455 ), released on January 13, 2026, credential prompt failures occurred 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 KB5077797 .

Secure Launch-capable devices might fail to shut down or hibernate

Symptoms

After installing this update, some PCs capable of using Secure Launch are unable to shut down or enter hibernation. Instead, the device restarts.

Workaround

This issue is fully resolved in Windows updates released on February 10, 2026 ( KB5075941 ), and in all updates released after that date. The update fixes the problem for devices that use Secure Launch and for devices Virtual Secure Mode (VSM) enabled.

An earlier fix that helped some Secure Launch devices was first released through the Microsoft Update Catalog in an OOB update on January 17, 2026 ( KB5077797 ), and later through Windows Update in another out‑of‑band update on January 24, 2026 ( KB5078132 ).

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

Symptom :

After installing this update, some applications may become unresponsive or encounter ...

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.

Authoritative references