Patch tracker / KB5082398

KB5082398: .NET Framework 3.5 on Windows Server Security Update (April 2026)

KB5082398 is a High security update for .NET Framework 3.5 on Windows Server, released 2026-04-14. It closes 3 CVEs with a maximum CVSS of 7.5. It is the 17th largest of the 60 updates Microsoft shipped that month, by CVEs closed.

Update summary

High
2026-04-14
Released
3
CVEs fixed
7.5
Max CVSS v3
High
Severity
Deploy this cycle
Fixes 3 CVEs for .NET Framework 3.5 on Windows Server. No confirmed in-the-wild exploitation in this set today.

Fixes 3 CVEs. Most severe CVSS 7.5 (High). EPSS exploit probability up to 2.4%. Among the top half of tracked Microsoft updates by EPSS exploit probability.

Senserva found thiswe track every release for this product line, so we can tell you this package is behind

A newer security update for Microsoft .NET Framework 3.5 on Windows Server 2012 has shipped since this one: KB5126042 (2026-09-08). 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 Update Catalog: download KB5082398Microsoft support article
Senserva AI Opinion for KB5082398

KB5082398 patches three CVEs in .NET runtimes, notably .NET 10.0 on Mac OS and Linux plus .NET 8.0, so this is a cross platform fix rather than a Windows only one. The highest rated flaw is High severity at CVSS 7.5, but EPSS sits at 2 percent and none of the three CVEs appear in CISA KEV or are ransomware linked. Exposure centers on servers and build hosts running these .NET versions, including Linux and macOS machines that often skip Windows patch cycles.

Do this: Inventory all hosts running .NET 10.0 on Linux and Mac OS and .NET 8.0, then apply the updated runtime and SDK builds and restart affected services.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5082398

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Full tracking and change history for KB5082398

Released
2026-04-14
Last changed
2026-04-14
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 KB5082398 is installed

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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.

CVESeverityCVSSEPSSExploited
CVE-2026-23666High7.52.4%No
CVE-2026-32226High7.52.4%No
CVE-2026-33116High7.52.4%No

Scope and sources

Affected products
Also released in April 2026

KB5082052

115 CVEs · Critical · exploited

KB5082060

121 CVEs · Critical · exploited

KB5082063

124 CVEs · Critical · exploited

KB5082123

107 CVEs · Critical · exploited

KB5082142

116 CVEs · Critical · exploited

KB5082198

87 CVEs · Critical · exploited

KB5082200

107 CVEs · Critical · exploited

KB5083768

119 CVEs · Critical · exploited

The full month, summarized: Microsoft Patch Tuesday.

Authoritative references
Official KB5082398 page (Microsoft Support)Microsoft Update CatalogMicrosoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
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