CVE-2021-36934: Microsoft Windows SAM Local Privilege Escalation Vulnerability

CISA Known Exploited Vulnerabilities

Name

Microsoft Windows SAM Local Privilege Escalation Vulnerability

Vendor

Microsoft

Product

Windows

Added to the catalog

2022-02-10

Due date for US federal agencies

2022-02-24

Weaknesses

CWE-1220

Catalog version

2026.10.30

If a Volume Shadow Copy (VSS) shadow copy of the system drive is available, users can read the SAM file which would allow any user to escalate privileges to SYSTEM level.

Required action (CISA)

Apply updates per vendor instructions.

Ransomware use: CISA does not mark known use of this vulnerability in ransomware campaigns.

Links in CISA's notes

• https://nvd.nist.gov/vuln/detail/CVE-2021-36934

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status

Analyzed

Published

2021-07-22T07:15:11.013

Last modified

2026-08-10T20:19:00.610

Weaknesses

NVD-CWE-Other

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.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934 (Patch, Vendor Advisory)
• http://packetstormsecurity.com/files/164006/HiveNightmare-AKA-SeriousSAM.html (Third Party Advisory, VDB Entry)
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36934 (Patch, Vendor Advisory)
• https://www.kb.cert.org/vuls/id/506989 (Third Party Advisory)
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36934 (US Government Resource)

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:41:59.479Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2021-36934

CVE record

Title (CNA)

Windows Elevation of Privilege Vulnerability

Assigner

microsoft

State

PUBLISHED

Published

2021-07-22T07:05:12.000Z

Updated

2026-08-10T15:11:26.655Z

Problem types

Elevation of Privilege

References

• Windows Elevation of Privilege Vulnerability

Read on 2026-11-03T01:08:29.240Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2021/36xxx/CVE-2021-36934.json

Detection rules (SigmaHQ)

SigmaHQ rules whose own tags name this CVE. Each rule page shows the rule as its author published it.

• HackTool - Typical HiveNightmare SAM File Export (status test, level high)