Patch tracker / KB5101000
KB5101000: .NET Framework 3.5 and 4.8.1 Security Update (July 2026)
KB5101000 is a High security update for .NET Framework 3.5 and 4.8.1, released 2026-07-14. It closes 17 CVEs with a maximum CVSS of 8.1. It is the 19th largest of the 61 updates Microsoft shipped that month, by CVEs closed.
Our data comes from Microsoft, CISA and other public sources, and it can be wrong or out of date. If you are unsure, check the linked source before you act, and tell us when we are wrong so we can fix it.
Update summary
Fixes 17 CVEs. Most severe CVSS 8.1 (High). EPSS exploit probability up to 4.0%. Among the top half of tracked Microsoft updates by EPSS exploit probability.
A newer security update for Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for x64-based Systems has shipped since this one: KB5120709 (2026-08-11). 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.
We checked Microsoft's support article for KB5101000 on 2026-10-05 and it lists no known issues. Read the article before broad deployment; Microsoft adds issues as reports come in, and we re-check on every refresh.
KB5101000 is a Security Update bundling .NET Framework 3.5 and 4.8.1 fixes for Windows 10 versions 21H2 and 22H2 across 32-bit, x64, and ARM64 systems. The per-update CVE detail for July 2026 is still provisional and not yet published by Microsoft, and the release document maps no named zero-days to this specific update. Because it touches both the legacy 3.5 runtime and 4.8.1 on the same machines, any application still bound to the older framework is in scope alongside modern ones.
Do this: Stage KB5101000 to a pilot ring covering both 21H2 and 22H2 endpoints and confirm .NET 3.5 dependent applications still start before broad deployment.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5101000
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5101000
- Released
- 2026-07-14
- Last changed
- 2026-09-24
- Changes tracked
- 4
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 KB5101000 is installed
Elevated PowerShell. No output means it is not installed.
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-2026-47304 | High | 8.1 | <1% | No |
| CVE-2026-50646 | High | 7.8 | 4.0% | No |
| CVE-2026-50649 | High | 7.8 | 4.0% | No |
| CVE-2026-50650 | High | 7.8 | <1% | No |
| CVE-2026-47302 | High | 7.5 | 1.2% | No |
| CVE-2026-50304 | High | 7.5 | 1.2% | No |
| CVE-2026-50355 | High | 7.5 | 1.2% | No |
| CVE-2026-50368 | High | 7.5 | 1.2% | No |
| CVE-2026-50411 | High | 7.5 | 1.2% | No |
| CVE-2026-50525 | High | 7.5 | 1.2% | No |
| CVE-2026-50527 | High | 7.5 | 1.2% | No |
| CVE-2026-50647 | High | 7.5 | 1.2% | No |
| CVE-2026-50648 | High | 7.5 | 1.2% | No |
| CVE-2026-50652 | High | 7.5 | 1.7% | No |
| CVE-2026-50653 | High | 7.5 | 1.2% | No |
| CVE-2026-50659 | Medium | 6.5 | <1% | No |
| CVE-2026-50324 | Medium | 5.9 | <1% | No |
Scope and sources
- Affected products
- Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for 32-bit Systems
- Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for ARM64-based Systems
- Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 21H2 for x64-based Systems
- Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for 32-bit Systems
- Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for ARM64-based Systems
- Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 Version 22H2 for x64-based Systems
- Also released in July 2026
KB5099444
182 CVEs · Critical · exploitedKB5099445
171 CVEs · Critical · exploitedKB5099535
258 CVEs · Critical · exploitedKB5099536
383 CVEs · Critical · exploitedKB5099538
308 CVEs · Critical · exploitedKB5099539
310 CVEs · Critical · exploitedKB5099540
322 CVEs · Critical · exploitedKB5101649
377 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.