Patch tracker / KB5100984
KB5100984: .NET Framework 3.5 Security Update (July 2026)
KB5100984 is a High security update for .NET Framework 3.5, released 2026-07-14. It closes 11 CVEs with a maximum CVSS of 8.1. It is the 38th largest of the 61 updates Microsoft shipped that month, by CVEs closed.
Update summary
Fixes 11 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 on Windows Server 2012 has shipped since this one: KB5127660 (2026-10-13). 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 1 known issue with this update.
- Microsoft is not currently aware of any issues in this update.
KB5100984 is a Security Update for .NET Framework 3.5 on Windows Server 2012, covering both full and Server Core installations. The CVE detail for this July 2026 cycle is still provisional, so Microsoft has not yet published which specific flaws this update fixes, and no named zero-days are mapped to it. It matters because Windows Server 2012 is on extended support only, so admins running legacy .NET 3.5 workloads on it have fewer fallback options if this patch is skipped.
Do this: Identify which Windows Server 2012 hosts still have .NET Framework 3.5 enabled and stage KB5100984 for testing ahead of production deployment.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5100984
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5100984
- Released
- 2026-07-14
- Last changed
- 2026-09-26
- Changes tracked
- 5
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 KB5100984 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5100984 (checked 2026-10-06). Verify against the article before acting.
Microsoft is not currently aware of any issues in this update.
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 | 4.9% | No |
| CVE-2026-50646 | High | 7.8 | 4.9% | No |
| CVE-2026-50649 | High | 7.8 | 4.9% | No |
| CVE-2026-50650 | High | 7.8 | 4.9% | No |
| CVE-2026-47302 | High | 7.5 | 4.9% | No |
| CVE-2026-50525 | High | 7.5 | 4.9% | No |
| CVE-2026-50527 | High | 7.5 | 4.9% | No |
| CVE-2026-50648 | High | 7.5 | 4.9% | No |
| CVE-2026-50652 | High | 7.5 | 4.9% | No |
| CVE-2026-50653 | High | 7.5 | 4.9% | No |
| CVE-2026-50659 | Medium | 6.5 | 4.9% | No |
Scope and sources
- Affected products
- Also released in July 2026
KB5099444
186 CVEs · Critical · exploitedKB5099445
175 CVEs · Critical · exploitedKB5099535
262 CVEs · Critical · exploitedKB5099536
390 CVEs · Critical · exploitedKB5099538
313 CVEs · Critical · exploitedKB5099539
315 CVEs · Critical · exploitedKB5099540
327 CVEs · Critical · exploitedKB5101649
384 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.