Microsoft Security Response CenterCVE-2026-69439

.NET and Visual Studio Elevation of Privilege Vulnerability

Heap-based buffer overflow in .NET and Visual Studio allows an unauthorized attacker to elevate privileges over a network.

Read the vendor bulletin Get alerts for NET 10.0 installed on Windows

8.8CVSS out of 10High severity

Scope

What the vendor says is affected

.NET 10.0 installed on Windows
.NET 8.0 installed on Windows
.NET 9.0 installed on Windows
Microsoft Visual Studio 2022 version 17.14
Microsoft Visual Studio 2026 version 18.9
.NET 11.0 installed on Windows

Versions the vendor lists as fixed

10.0.12
8.0.31
9.0.20
17.14.40
18.9.3
11.0 RC1

Next step

What the vendor recommends

Release Notes Install KB5126106. Install KB5126104. Install KB5126105.

Review the complete instructions on the vendor's site

Timeline

When this advisory changed

Sep 8, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Sep 8, 2026 at 7:15 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Sep 13, 2026 at 2:40 AM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-69439View CVSS, KEV, EPSS, and threat context

Source

Start with the vendor's bulletin

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Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-69439
Last source check: Sep 13, 2026 at 2:40 AM UTC

Open the official bulletin How SecurityAlert builds this record

Your environment

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Test the update or mitigation through your normal change process.

Watch NET 10.0 installed on Windows

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

When this advisory changed

CVEs named in this advisory

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