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Full vulnerability report · 2021
CVE-2021-34484High confidence

Microsoft Windows User Profile Service Privilege Escalation Vulnerability

Microsoft · Windows

7.8HighCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2022-04-21 as the remediation due date.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 31 Mar 2022

Evidence used

  • CISA confirms exploitation in the wild.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 21.83% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Microsoft Windows and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-21139

CISA KEV mirrored by ENISA

Windows User Profile Service Elevation of Privilege Vulnerability

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 31 Mar 2022. Evidence sources: cisa_kev.
ENISA score
7.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch now

CISA confirms exploitation in the wild and lists 2022-04-21 as the remediation due date.

Patch available
01

What, why and how

Microsoft Windows User Profile Service contains an unspecified vulnerability that allows for privilege escalation.

What

Microsoft Windows User Profile Service contains an unspecified vulnerability that allows for privilege escalation.

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

What

Microsoft Windows User Profile Service contains an unspecified vulnerability that allows for privilege escalation.

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2022-03-31.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → Improper Privilege Management → gain additional privileges
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-269 ↗

CWE-269: Improper Privilege Management. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
Privilege escalationCWE-269CISA KEV
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2021-21139Known-exploited evidence recorded

Windows User Profile Service Elevation of Privilege Vulnerability

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210818Security Bulletin 18 Aug 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 18 Aug 2021, published on 18 August 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-618Multiples vulnérabilités dans Microsoft Windows

d?id=CVE-2021-26424 Référence CVE CVE-2021-26425 https://www.cve.org/CVERecord?id=CVE-2021-26425 Référence CVE CVE-2021-26426 https://www.cve.org/CVERecord?id=CVE-2021-26426 Référence CVE CVE-2021-26431 https://www.cve.org/CVERecord?id=CVE-2021-26431 Référence CVE CVE-2021-26432 https://www.cve.org/CVERecord?id=CVE-2021-26432 Référence CVE CVE-2021-26433 https://www.cve.org/CVERecord?id=CVE-2021-26433 Référence CVE CVE-2021-34480 https://www.cve.org/CVERecord?id=CVE-2021-34480 Référence CVE CVE-2021-34481 https://www.cve.org/CVERecord?id=CVE-2021-34481 Référence CVE CVE-2021-34483 https://www.cve.org/CVERecord?id=CVE-2021-34483 Référence CVE CVE-2021-34484 https://www.cve.org/CVERecord?id=CVE-2021-34484 Référence CVE CVE-2021-34486 https://www.cve.org/CVERecord?id=CVE-2021-34486 Référence CVE CVE-2021-34487 https://www.cve.org/CVERecord?id=CVE-2021-34487 Référence CVE CVE-2021-34530 https://www.cve.org/CVERecord?id=CVE-2021-34530 Référence CVE CVE-2021-34533 https://www.cve.org/CVERecord?id=CVE-2021-34533 Référence CVE CVE-2021-34534 https://www.cve.org/CVERecord?id=CVE-2021-34534 Référence CVE CVE-2021-34535 https://www.cve.org/CVERecord?id=CVE-2021-34535 Référence CVE CVE-2021-34536 https://www.cve.org/CVERecord?id=CVE-2021-34536 Référence CVE CVE-2021-34537 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-002319複数の Microsoft Windows 製品 における権限を昇格される脆弱性

複数の Microsoft Windows 製品 には、Windows User Profile Service に不備があるため、権限を昇格される脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5362MS 8월 보안 위협에 따른 정기 보안 업데이트 권고

FS ONCRPC XDR Driver CVE-2021-36926 NFS ONCRPC XDR 드라이버용 Windows 서비스 정보 공개 취약성 Windows Services for NFS ONCRPC XDR Driver CVE-2021-26433 NFS ONCRPC XDR 드라이버용 Windows 서비스 정보 공개 취약성 Windows Services for NFS ONCRPC XDR Driver CVE-2021-26432 NFS ONCRPC XDR 드라이버용 Windows 서비스 원격 코드 실행 취약성 Windows Storage Spaces Controller CVE-2021-34536 저장소 공간 컨트롤러 권한 상승 취약성 Windows TCP/IP CVE-2021-26424 Windows TCP/IP 원격 코드 실행 취약성 Windows Update CVE-2021-36948 Windows Update Medic Service 권한 상승 취약성 Windows Update Assistant CVE-2021-36945 Windows 10 업데이트 길잡이 권한 상승 취약성 Windows Update Assistant CVE-2021-26431 Windows 복구 환경 에이전트 권한 상승 취약성 Windows User Profile Service CVE-2021-34484 Windows 사용자 프로필 서비스 권한 상승 취약성 Windows User Profile Service CVE-2021-26426 Windows 사용자 계정 프로필 사진 권한 상승 취약성 Servicing Stack Updates - 최신 서비스 스택 업데이트( ADV990001 ) ##### □ 작성 : 침해사고분석단 취약점분석팀

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 12 Aug 2021 · Last source change 10 Aug 2026, 15:10 UTC · CWE-269 · Improper Privilege Management

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-21139
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCISA KEV
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    10.0.10240.0 < 10.0.10240.19022; 10.0.14393.0 < 10.0.14393.4583; 10.0.17763.0 < 10.0.17763.2114; 10.0.0 < 10.0.17763.2114; 10.0.0 < 10.0.18363.1734; 10.0.0 < 10.0.19041.1165; 10.0.0 < 10.0.19042.1165; 10.0.0 < 10.0.19043.1165 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Windows 10 Version 1507: 10.0.10240.0 < 10.0.10240.19022; Windows 10 Version 1607: 10.0.14393.0 < 10.0.14393.4583; Windows 10 Version 1809: 10.0.17763.0 < 10.0.17763.2114, 10.0.0 < 10.0.17763.2114; Windows 10 Version 1909: 10.0.0 < 10.0.18363.1734; Windows 10 Version 2004: 10.0.0 < 10.0.19041.1165; Windows 10 Version 20H2: 10.0.0 < 10.0.19042.1165; Windows 10 Version 21H1: 10.0.0 < 10.0.19043.1165; Windows 7: 6.1.0 < 6.1.7601.25685; Windows 7 Service Pack 1: 6.1.0 < 6.1.7601.25685; Windows 8.1: 6.3.0 < 6.3.9600.20094; Windows Server 2008 R2 Service Pack 1: 6.1.7601.0 < 6.1.7601.25685; Windows Server 2008 R2 Service Pack 1 (Server Core installation): 6.1.7601.0 < 6.1.7601.25685; Windows Server 2008 Service Pack 2: 6.0.6003.0 < 6.0.6003.21192; Windows Server 2008 Service Pack 2 (Server Core installation): 6.0.6003.0 < 6.0.6003.21192; Windows Server 2012: 6.2.9200.0 < 6.2.9200.23435; Windows Server 2012 (Server Core installation): 6.2.9200.0 < 6.2.9200.23435; Windows Server 2012 R2: 6.3.9600.0 < 6.3.9600.20094; Windows Server 2012 R2 (Server Core installation): 6.3.9600.0 < 6.3.9600.20094; Windows Server 2016: 10.0.14393.0 < 10.0.14393.4583; Windows Server 2016 (Server Core installation): 10.0.14393.0 < 10.0.14393.4583; Windows Server 2019: 10.0.17763.0 < 10.0.17763.2114; Windows Server 2019 (Server Core installation): 10.0.17763.0 < 10.0.17763.2114; Windows Server version 2004: 10.0.0 < 10.0.19041.1165; Windows Server version 20H2: 10.0.0 < 10.0.19042.1165 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-21139↗CISA KEV record↗CVE authority or vendor reference↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-34484 · cve.blacktree.nl