---
id: CVE-2021-36934
title: >-
  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
summary: >-
  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
  vulnera…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
vendor: microsoft
product: windows_10_1809
affected:
  - windows_10_1809 < 10.0.17763.2114
  - windows_10_1909 < 10.0.18363.1734
  - windows_10_2004 < 10.0.19041.1165
  - windows_10_20h2 < 10.0.19042.1165
  - windows_10_21h1 < 10.0.19043.1165
patched:
  - windows_10_1809 10.0.17763.2114
  - windows_10_1909 10.0.18363.1734
  - windows_10_2004 10.0.19041.1165
  - windows_10_20h2 10.0.19042.1165
  - windows_10_21h1 10.0.19043.1165
published: '2021-07-22'
updated: '2026-08-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-36934'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934'
    label: secure@microsoft.com
  - url: >-
      http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.kb.cert.org/vuls/id/506989'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - kev
  - in-the-wild
  - exploit-available
epss: 0.67252
epssPercentile: 0.9928
kev: true
kevDateAdded: '2022-02-10'
kevDueDate: '2022-02-24'
kevRansomware: false
exploited: true
ingestedAt: '2026-08-11T16:47:01.027Z'
exploits:
  github: 24
  githubRepos:
    - 'https://github.com/HuskyHacks/ShadowSteal'
    - 'https://github.com/JoranSlingerland/CVE-2021-36934'
    - 'https://github.com/n3tsurge/CVE-2021-36934'
  metasploit:
    - post/windows/gather/credentials/windows_sam_hivenightmare
  checkedAt: '2026-09-25T08:20:39.591Z'
exploitAvailable: true
---

## Overview

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.

## Affected

- `windows_10_1809 < 10.0.17763.2114`
- `windows_10_1909 < 10.0.18363.1734`
- `windows_10_2004 < 10.0.19041.1165`
- `windows_10_20h2 < 10.0.19042.1165`
- `windows_10_21h1 < 10.0.19043.1165`

## Remediation

Upgrade past the affected range:

- `windows_10_1809 10.0.17763.2114`
- `windows_10_1909 10.0.18363.1734`
- `windows_10_2004 10.0.19041.1165`
- `windows_10_20h2 10.0.19042.1165`
- `windows_10_21h1 10.0.19043.1165`