.NET Core Remote Code Execution Vulnerability

Out-of-bounds write in .NET allows an unauthorized attacker to execute code locally.

Read the vendor bulletin Get alerts for Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows

7.8CVSS out of 10High severity

Scope

What the vendor says is affected

Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows 10 Version 1607 for 32-bit Systems
Microsoft .NET Framework 3.5 on Windows Server 2012
Microsoft .NET Framework 3.5 on Windows Server 2012 (Server Core installation)
Microsoft .NET Framework 3.5 on Windows 11 Version 26H1 for ARM64-based Systems
Microsoft .NET Framework 3.5 on Windows Server 2012 R2
Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows 10 Version 1607 for x64-based Systems
Microsoft .NET Framework 3.5 on Windows Server 2012 R2 (Server Core installation)
Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for 32-bit Systems
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for 32-bit Systems
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for ARM64-based Systems
Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2016 (Server Core installation)
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for x64-based Systems
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2019
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2019 (Server Core installation)
Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for x64-based Systems
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for ARM64-based Systems
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 22H2 for x64-based Systems
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022 (Server Core installation)
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for 32-bit Systems
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019 (Server Core installation)
Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022
Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 21H2 for x64-based Systems

Versions the vendor lists as fixed

2.0.50727.8984 & 3.0.30729.8980 & 4.7.4144.0
2.0.50727.8984 & 3.0.30729.8980
2.0.50727.9183 & 3.0.30729.9169
2.0.50727.9070 & 3.0.30729.9068 & 4.8.4805.0
2.0.50727.9070 & 3.0.30729.9068 & 4.7.4144.0
2.0.50727.9183 & 3.0.30729.9169 & 4.8.4805.0
2.0.50727.9183 & 3.0.30729.9169 & 4.8.9343.0
4.7.4144.0
4.8.4805.0
18.8.3
17.14.38
9.0.19
8.0.30
10.0.11
2.0.50727.9183 & 3.0.30729.9169 & 4.8.9344.0
4.8.9344.0

Next step

What the vendor recommends

Install KB5120418. Install KB5120716. Install KB5120747. Install KB5120695. Install KB5120703. Install KB5120698. Install KB5120701. Install KB5120705. Install KB5120709. Install KB5120714. Install KB5120700. Install KB5120699. Install KB5120702. Install KB5120704. Install KB5122105. Install KB5122104. Install KB5122106. Install KB5120708. Install KB5120710. Install KB5120713. Install KB5120706. Install KB5120711.

Review the complete instructions on the vendor's site

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

Aug 20, 2026 at 7:00 PM UTC
- The vendor changed its remediation guidance.

Timeline

When this advisory changed

Aug 11, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Aug 13, 2026 at 7:00 AM UTC
Updated by Microsoft Security Response Center
The vendor changed the advisory after it was first published.
Aug 20, 2026 at 6:50 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Sep 2, 2026 at 5:15 PM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-70354View 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-2026-70354
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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Read the vendor's prerequisites and exceptions.
Test the update or mitigation through your normal change process.

Watch Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 on Windows

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

What changed in later vendor updates

When this advisory changed

CVEs named in this advisory

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