CVE-2021-34477

Local privilege escalation via world-writable install scripts

Published Jul 14, 2021 · Updated Aug 10, 2026

Improper permissions in .NET Install Tool 1.1.0 and .NET Education Bundle SDK Install Tool 0.6.0 allow local users to gain privileges. InstallScriptAcquisitionWorker writes a downloaded install script and assigns mode 0777, permitting other local accounts to replace executable content before the extension launches it. Exploitation requires low-privileged local access and an extension acquisition flow; injected code then runs with the victim account's privileges.

CVSS severity7.8
High
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper permissions in .NET Install Tool 1.1.0 and .NET Education Bundle SDK Install Tool 0.6.0 allow local users to gain privileges. InstallScriptAcquisitionWorker writes a downloaded install script and assigns mode 0777, permitting other local accounts to replace executable content before the extension launches it. Exploitation requires low-privileged local access and an extension acquisition flow; injected code then runs with the victim account's privileges.

The record

CVE
CVE-2021-34477
Published
Jul 14, 2021
Updated
Aug 10, 2026
Vendor
Microsoft
Product
.NET Education Bundle SDK Install Tool
Classifications
CWE-269, T1574
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 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=0.0.0 <1.2.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · .NET Education Bundle SDK Install Toolversion=0.0.0 <1.2.0
Microsoft · .NET Install Tool for Extension Authorsversion=1.0.0 <0.7.0

Published CVSS scores

7.8MicrosoftCVSS: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

CWE-269Improper Privilege Management
T1574Hijack Execution Flow

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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