CVE-2020-1066

Local privilege escalation via COM object activation

Published May 21, 2020 · Updated Aug 19, 2026

Elevation of privilege in Microsoft .NET Framework 3.0 SP2 and 3.5.1 allows local users to gain elevated privileges via a malicious program. The flaw occurs when .NET Framework activates COM objects, but Microsoft has not disclosed the faulty check or object-selection logic. Exploitation requires prior local-machine access and execution of a malicious program; successful exploitation raises that program's privilege level.

CVSS severity7.8
High
EPSS probability2.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Elevation of privilege in Microsoft .NET Framework 3.0 SP2 and 3.5.1 allows local users to gain elevated privileges via a malicious program. The flaw occurs when .NET Framework activates COM objects, but Microsoft has not disclosed the faulty check or object-selection logic. Exploitation requires prior local-machine access and execution of a malicious program; successful exploitation raises that program's privilege level.

The record

CVE
CVE-2020-1066
Published
May 21, 2020
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Microsoft .NET Framework 3.0 Service Pack 2
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.0.0 <publication

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft .NET Framework 3.0 Service Pack 2version=3.0.0 <publication
Microsoft · Microsoft .NET Framework 3.5.1version=3.5.0 <publication

Published CVSS scores

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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