Patch tracker / KB5073455
KB5073455: Windows 10 Version 1809 for 32-bit Sys Security Update (January 2026)
KB5073455 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. The most likely of them to be attacked is CVE-2026-20962, which FIRST.org rates at 75% probability of exploitation in the next 30 days.
Update summary
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 10% of tracked Microsoft updates by EPSS exploit probability.
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, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.
Microsoft documents 3 known issues with this update.
- 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
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.
Senserva AI Opinion and rich prompt for KB5073455
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5073455
- Released
- 2026-01-13
- Last changed
- 2026-08-04
- Changes tracked
- 3
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 KB5073455 is installed
Elevated PowerShell. No output means it is not installed.
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.
Scope and sources
- Affected products
- Also released in January 2026
KB5002822
6 CVEs · Critical · exploitedKB5002825
7 CVEs · Critical · exploitedKB5002828
7 CVEs · Critical · exploitedKB5073379
86 CVEs · Critical · exploitedKB5073450
80 CVEs · Critical · exploitedKB5073457
78 CVEs · Critical · exploitedKB5073722
54 CVEs · Critical · exploitedKB5073723
73 CVEs · Critical · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.