Patch tracker / KB5087055
KB5087055: .NET Framework 3.5 AND 4.8.1 on Security Update (May 2026)
KB5087055 is a High security update for .NET Framework 3.5 AND 4.8.1 on, released 2026-05-12. It closes 2 CVEs with a maximum CVSS of 7.3. It is the 21st largest of the 61 updates Microsoft shipped that month, by CVEs closed.
Update summary
Fixes 2 CVEs. Most severe CVSS 7.3 (High). EPSS exploit probability up to <1%. Among the lower 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 11 version 26H1 for x64-based Systems has shipped since this one: KB5101002 (2026-07-14). 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.
KB5087055 patches two CVEs across .NET 8.0, 9.0, and 10.0 on Windows, with the more serious rated High at CVSS 7.3. Anyone running .NET workloads on Windows across those three runtime versions is exposed, so a single machine may need multiple runtime updates. EPSS sits at 1 percent and neither CVE is in CISA KEV or linked to ransomware, so this is a routine but broad patch rather than an emergency.
Do this: Inventory which .NET runtime versions (8.0, 9.0, 10.0) are installed on your Windows hosts and apply KB5087055 to each affected runtime during your next patch cycle.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5087055
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5087055
- Released
- 2026-05-12
- Last changed
- 2026-09-26
- Changes tracked
- 2
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 KB5087055 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5087055 (checked 2026-08-06). 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-2026-32177 | High | 7.3 | 2.4% | No |
| CVE-2026-35433 | High | 7.3 | 2.4% | No |
Scope and sources
- Affected products
- Also released in May 2026
KB5002863
9 CVEs · High · exploitedKB5002868
9 CVEs · High · exploitedKB5002870
9 CVEs · High · exploitedKB5094139
1 CVE · High · exploitedKB5094140
1 CVE · High · exploitedKB5094142
1 CVE · High · exploitedKB5094144
1 CVE · High · exploitedKB5078943
3 CVEs · CriticalThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.