Patch tracker / KB5087058
KB5087058: .NET 8.0 installed on Windows Security Update (May 2026)
KB5087058 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.
KB5087058 patches two vulnerabilities (CVE-2026-35433 and CVE-2026-32177) across .NET 8.0, 9.0, and 10.0 running on Windows, with the more serious rated High at CVSS 7.3. Anyone hosting applications or services built on these .NET runtimes is exposed, and because three major versions are covered you likely have mixed installs across your fleet. Exploitation pressure is currently low, with EPSS at 1 percent and no CISA KEV or ransomware association, so this is a plan-and-schedule fix rather than an emergency.
Do this: Inventory which .NET 8.0, 9.0, and 10.0 runtimes are deployed on your Windows servers and workstations, then apply KB5087058 to each affected version during your next patch window.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5087058
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5087058
- 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 KB5087058 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5087058 (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.