Windows Elevation of Privilege Vulnerability

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Summary

CVECVE-2021-36934
StatePUBLISHED
Assignermicrosoft
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-07-22 07:15:11 UTC
Updated2026-08-10 20:19:00 UTC
DescriptionAn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.672520000 probability, percentile 0.992440000 (date 2026-08-27)

CISA KEV: Listed on 2022-02-10; due 2022-02-24; ransomware use Unknown

Problem Types: NVD-CWE-Other | Elevation of Privilege | CWE-noinfo Not enough information

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1[email protected]Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:T/RC:C
2.0[email protected]Primary4.6AV:L/AC:L/Au:N/C:P/I:P/A:P

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 Breakdown

Access Vector
Local
Access Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:L/AC:L/Au:N/C:P/I:P/A:P

CISA Known Exploited Vulnerability

VendorMicrosoft
ProductWindows
NameMicrosoft Windows SAM Local Privilege Escalation Vulnerability
Required ActionApply updates per vendor instructions.
Noteshttps://nvd.nist.gov/vuln/detail/CVE-2021-36934

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Microsoft Windows 10 1809 All All All All
Operating System Microsoft Windows 10 1909 All All All All
Operating System Microsoft Windows 10 2004 All All All All
Operating System Microsoft Windows 10 20h2 All All All All
Operating System Microsoft Windows 10 21h1 All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Microsoft Windows 10 Version 1809 affected 10.0.17763.0 10.0.17763.2114 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows 10 Version 1809 affected 10.0.0 10.0.17763.2114 custom ARM64-based Systems
CNA Microsoft Windows 10 Version 1909 affected 10.0.0 10.0.18363.1734 custom 32-bit Systems, ARM64-based Systems, x64-based Systems
CNA Microsoft Windows 10 Version 2004 affected 10.0.0 10.0.19041.1165 custom 32-bit Systems, ARM64-based Systems, x64-based Systems
CNA Microsoft Windows 10 Version 20H2 affected 10.0.0 10.0.19042.1165 custom 32-bit Systems, ARM64-based Systems
CNA Microsoft Windows 10 Version 21H1 affected 10.0.0 10.0.19043.1165 custom 32-bit Systems, ARM64-based Systems, x64-based Systems

References

ReferenceSourceLinkTags
www.cisa.gov/known-exploited-vulnerabilities-catalog 134c704f-9b21-4f2e-91b3-4a467353bcc0 www.cisa.gov US Government Resource
HiveNightmare AKA SeriousSAM ≈ Packet Storm af854a3a-2127-422b-91ae-364da2661108 packetstormsecurity.com Third Party Advisory, VDB Entry
www.kb.cert.org/vuls/id/506989 af854a3a-2127-422b-91ae-364da2661108 www.kb.cert.org Third Party Advisory
Security Update Guide - Microsoft Security Response Center af854a3a-2127-422b-91ae-364da2661108 portal.msrc.microsoft.com Patch, Vendor Advisory
msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36934 [email protected] msrc.microsoft.com Patch, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
CISA Known Exploited Vulnerabilities catalog CISA www.cisa.gov kev

Additional Advisory Data

SourceTimeEvent
ADP2022-02-10T00:00:00.000ZCVE-2021-36934 added to CISA KEV

Legacy QID Mappings

  • 91797 Microsoft Windows Elevation of Privilege Vulnerability (CVE-2021-36934)(Zero-day)(HiveNightmare/SeriousSAM)

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