CVE-2026-97801: .NET Framework Tampering Vulnerability

Overview

Severity

High (CVSS 7.5)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C

Category

Tampering

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Oct

Released

2026-10-13

EPSS Score

0.61% (percentile: 47.9%)

Description

Improper validation of specified type of input in .NET Framework allows an unauthorized attacker to perform tampering over a network.

Affected Products (27)

Developer Tools

• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 version 21H2
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 10 version 22H2
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 24H2
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 25H2
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2025
• Microsoft .NET Framework 4.8.1 on Windows 11 version 26H1
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 23H2
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows Server 2022
• Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 26H2
• Microsoft .NET Framework 3.5 on Windows 11 version 26H1
• Microsoft .NET Framework 3.5 on Windows Server 2012
• 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
• 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 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2019
• Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 version 1809
• Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 version 1809
• Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 version 21H2
• Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 version 22H2
• Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019
• Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2022
• Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012
• Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 on Windows Server 2012 R2
• Microsoft .NET Framework 4.8 on Windows 10 version 1607
• Microsoft .NET Framework 4.8 on Windows Server 2012
• Microsoft .NET Framework 4.8 on Windows Server 2012 R2
• Microsoft .NET Framework 4.8 on Windows Server 2016

Security Updates (19)

• 5127689
• 5127690
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• 5127696
• 5127660
• 5127664
• 5126868
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• 5127685
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• 5127687
• 5127667
• 5127668
• 5127684
• 5127686
• 5127688

Revision History

• 2026-10-13: Information published.