What’s Vulnerable › Vulnerabilities

CVE-2020-1066: .NET Framework Elevation of Privilege Vulnerability

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-05-21 · updated 2026-08-19

Description

An elevation of privilege vulnerability exists in .NET Framework which could allow an attacker to elevate their privilege level. To exploit the vulnerability, an attacker would first have to access the local machine, and then run a malicious program. The update addresses the vulnerability by correcting how .NET Framework activates COM objects.

Affected products

• Microsoft .NET Framework: 3.0-sp2, 3.5.1
• Microsoft .NET Framework 3.0 Service Pack 2: from 3.0.0 before publication — fixed in publication
• Microsoft .NET Framework 3.5.1: from 3.5.0 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft .NET Framework 3.0 Service Pack 2 publication; Microsoft .NET Framework 3.5.1 publication. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-1066
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1066

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