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

> A local attacker can elevate privileges by running a malicious program that exploits how .NET Framework activates COM objects.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 May 2020
- **Updated:** 19 Aug 2026
- **Also known as:** GHSA-jp98-j3r8-w99v

## What is CVE-2020-1066?

CVE-2020-1066 is a high-severity vulnerability in Microsoft .Net Framework, published on 21 May 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

## Which versions are affected by CVE-2020-1066?

It affects 1 product.


Products: Microsoft .Net Framework.

## How do I fix CVE-2020-1066?

No fix has been published for CVE-2020-1066 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1066 being exploited?

There is no known exploitation of CVE-2020-1066 in the wild and no public exploit code.

Public exploit code:

- CVE-2020-1066-EXP支持Windows 7和Windows Server 2008 R2操作系统 (github_poc): https://github.com/cbwang505/CVE-2020-1066-EXP
- https://github.com/xyddnljydd/cve-2020-1066 (github_poc): https://github.com/xyddnljydd/cve-2020-1066

## Other vulnerabilities in Microsoft .Net Framework

- [CVE-2020-0646](https://insights.sbomify.com/CVE-2020-0646/): Microsoft .NET Framework Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2017-8759](https://insights.sbomify.com/CVE-2017-8759/): Microsoft .NET Framework Remote Code Execution (high 7.8, exploited in the wild)
- [CVE-2015-1671](https://insights.sbomify.com/CVE-2015-1671/): Microsoft Windows Remote Code Execution (high 7.8, exploited in the wild)
- [CVE-2024-29059](https://insights.sbomify.com/CVE-2024-29059/): Microsoft .NET Framework Information Disclosure (high 7.5, exploited in the wild)
- [CVE-2014-4073](https://insights.sbomify.com/CVE-2014-4073/): Privilege escalation in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-1066 and fix it if it is affected.

What it is: CVE-2020-1066 is a high-severity vulnerability in Microsoft .Net Framework, published on 21 May 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-1066 in the wild and no public exploit code.

Affected product: Microsoft .Net Framework. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-1066/ (Markdown: https://insights.sbomify.com/CVE-2020-1066/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1066
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1066
- OSV: https://osv.dev/vulnerability/CVE-2020-1066

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1066/
Summaries are generated and may contain mistakes; the official description above is the record.