CVE-2026-97801: .NET Framework Tampering Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-31
Weakness: CWE-1287

Description

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

Affected products

Microsoft .NET Framework 3.5: from 3.5.0 before 2.0.50727.9188 AND 3.0.30729.9171 — fixed in 2.0.50727.9188 AND 3.0.30729.9171
Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2: from 3.0.0.0 before 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0 — fixed in 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0
Microsoft .NET Framework 3.5 AND 4.7.2: from 4.7.0 before 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0 — fixed in 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0
Microsoft .NET Framework 3.5 AND 4.8: from 4.8.0 before 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0 — fixed in 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0
Microsoft .NET Framework 3.5 AND 4.8.1: from 4.8.1 before 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0 — fixed in 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0
Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2: from 4.7.0 before 4.7.4150.0 — fixed in 4.7.4150.0
Microsoft .NET Framework 4.8: from 4.8.0 before 4.8.4811.0 — fixed in 4.8.4811.0
Microsoft .NET Framework 4.8.1: from 4.8.0.0 before 4.8.9363.0 — fixed in 4.8.9363.0

How to fix

Upgrade to a fixed version: Microsoft .NET Framework 3.5 2.0.50727.9188 AND 3.0.30729.9171; Microsoft .NET Framework 3.5 AND 4.6.2/4.7/4.7.1/4.7.2 2.0.50727.8987 AND 3.0.30729.8982 AND 4.7.4150.0; Microsoft .NET Framework 3.5 AND 4.7.2 2.0.50727.9073 AND 3.0.30729.9070 AND 4.7.4150.0; Microsoft .NET Framework 3.5 AND 4.8 2.0.50727.9073 AND 3.0.30729.9070 AND 4.8.4811.0; Microsoft .NET Framework 3.5 AND 4.8.1 2.0.50727.9188 AND 3.0.30729.9171 AND 4.8.9363.0; Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2 4.7.4150.0; Microsoft .NET Framework 4.8 4.8.4811.0; Microsoft .NET Framework 4.8.1 4.8.9363.0. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97801

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