Patch tracker / KB5087059
KB5087059: .NET 8.0 installed on Windows Security Update (May 2026)
KB5087059 is a High security update for .NET 8.0 installed on Windows, 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 .NET 10.0 installed on Windows has shipped since this one: KB5100984 (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.
KB5087059 patches two CVEs (CVE-2026-35433 and CVE-2026-32177) across .NET 8.0, 9.0, and 10.0 runtimes installed on Windows, with a highest rating of High severity at CVSS 7.3. Anyone running applications built on these three .NET versions is exposed, but exploitation risk is currently low given the 1% EPSS and no listing in CISA KEV. The unusual point here is the breadth: three concurrent .NET major versions are affected by the same update, so mixed-version environments need to inventory all of them.
Do this: Enumerate which .NET 8.0, 9.0, and 10.0 runtimes are present on your Windows hosts, then deploy KB5087059 to cover every version found.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5087059
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5087059
- Released
- 2026-05-12
- Last changed
- 2026-05-12
- Changes tracked
- 1
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 KB5087059 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5087059 (checked 2026-08-07). 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.