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CVE-2021-34484

INDEX BUILT · 2026-09-20

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Windows User Profile Service Elevation of Privilege Vulnerability

CVE-2021-344844 of 4 sources documented this
68

rank 68 = 40 + 12 + 1 + 9 + 6

rank@v1 · this cycle

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.21827 · CISA KEV listed  ·  without this subject the record ranks 28

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 4.6, from NVD  ·  without this subject the record ranks 56

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

rose on 2025-11-18  ·  without this subject the record ranks 67

How much of the world it touches

NVD CPE configurations

13 products in the CPE ranges  ·  without this subject the record ranks 59

Someone else already set the date

CISA KEV remediation due date

CISA remediation date held  ·  without this subject the record ranks 62

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$1.09Mover the next 30 days, if this record is yours
Movement-$601,000on 2025-11-21, the last material move, 9 months before this reading
Basisassumeda published average, not your estate

$1.09M = $4.99M incident cost x 1 exposure x 0.21827 likelihood

udv@v1 · unaudited · wrong for you until you say what you run

$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.

Hindsight · the state

0.21827EPSSKEV · LISTED
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationin the wild · KEVreceipt
Defensefix version namedreceipt
Movementrisenreceipt
PLATEAU10Minimal movement since 2026-06-15, 85 days at 0.22, as of 2026-09-08. arc-rules@v1

Foresight · where to check next

No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.

Color is a claim, not decoration:the hostile worldthe defenseno signal

Sources disagree here.

Severity score
Microsoft7.8 HIGHreceipt
NVD4.6 MEDIUMreceipt
Scoring standard
MicrosoftCVSS v3.1receipt
NVDCVSS v2.0receipt

Both shown, dated. We don't pick winners. disagreement-rules@v1

Running Microsoft Windows 10 Version 1507? Check your version

A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.

Watch this record

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What counts as a move

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Record your call

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AcceptDeferPatch by…Not affectedMitigated

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Harm, if it fires from the vector and the weakness

Written for the ticket you're about to file.

Reachneeds local access · low privileges required · no user interaction · low attack complexityreceipt
ImpactComplete confidentiality, integrity and availability lossreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classNo CWE mapping in held sources.
Ransomware campaign useUnknown to CISAreceipt

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

Fixed in10.0.10240.19022; 10.0.14393.4583; 10.0.17763.2114; 10.0.18363.1734; 10.0.19041.1165; 10.0.19042.1165; 10.0.19043.1165; 6.1.7601.25685; 6.3.9600.20094…receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.
CISA remediation statusoverdue since 2022-04-21receipt
CISA required actionApply updates per vendor instructions.receipt
Published to CISA KEV231 daysderived

Exploit Status & Known PoCs a ladder, not a score

Current rung: Exploited in the wild · CISA KEV listed, 2022-03-31.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed2022-03-31receipt
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA7.8 HIGHreceipt
CVSS, NVD4.6 MEDIUMreceipt
Exploit probability0.21827 · top 2% of all CVEsreceipt
Blast breadth3 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes67 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productMicrosoft Windows 10 Version 1507; Microsoft Windows 10 Version 1607; Microsoft Windows 10 Version 1809; Microsoft Windows 10 Version 1909; Microsoft Windows 10 Version 2004…receipt
Published rangesmicrosoft windows 10 1507 < 10.0.10240.19022; microsoft windows 10 1607 < 10.0.14393.4583; microsoft windows 10 1809 < 10.0.17763.2114; microsoft windows 10 1909 < 10.0.18363.1734receipt
Show all 13 published ranges
microsoft windows 10 1507 < 10.0.10240.19022
microsoft windows 10 1607 < 10.0.14393.4583
microsoft windows 10 1809 < 10.0.17763.2114
microsoft windows 10 1909 < 10.0.18363.1734
microsoft windows 10 2004 < 10.0.19041.1165
microsoft windows 10 20h2 < 10.0.19042.1165
microsoft windows 10 21h1 < 10.0.19043.1165
microsoft windows server 2004 < 10.0.19041.1165
microsoft windows server 2008 r2
microsoft windows server 2012 r2
microsoft windows server 2016 < 10.0.14393.4583
microsoft windows server 2019 < 10.0.17763.2114
microsoft windows server 20h2 < 10.0.19042.1165
Fixed in10.0.10240.19022; 10.0.14393.4583; 10.0.17763.2114; 10.0.18363.1734; 10.0.19041.1165; 10.0.19042.1165; 10.0.19043.1165; 6.1.7601.25685; 6.3.9600.20094…receipt

A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.

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What it is stated by the CNA

Windows User Profile Service Elevation of Privilege Vulnerability receipt

NVD's analysis a second authority

severity
4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P
affected versions
microsoft windows 10 1507 < 10.0.10240.19022; microsoft windows 10 1607 < 10.0.14393.4583; microsoft windows 10 1809 < 10.0.17763.2114; and 10 more, listed in full below
also scored by
[email protected] 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H · [email protected] 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

The CNA scored it 7.8 and NVD 4.6. Both are shown because both were published; we do not pick one.

check it yourself msrc.microsoft.com receipt

Dated events

2022-01-06EPSS moved 0.05 to 0.182022-03-31Added to CISA KEV2022-04-21CISA remediation due2025-03-29EPSS moved 0.06 to 0.232026-08-11EPSS moved 0.16 to 0.22

Movement the material steps

13 Aug 20210.00416
6 Jan 20220.17642 · crossed 0.10
4 Feb 20220.01372 · crossed 0.10
7 Mar 20230.00134 · scoring model v2023.03.01
17 Mar 20250.06063 · scoring model v2025.03.14
29 Mar 20250.22577 · crossed 0.10
30 Mar 20250.06272 · crossed 0.10
18 Nov 20250.15112 · crossed 0.10
21 Nov 20250.03076 · crossed 0.10
15 Jun 20260.14393 · crossed 0.10 · scoring model v2026.06.15
8 Sep 20260.21827
Show all 56 observations
13 Aug 20210.00416
24 Aug 20210.04557
6 Jan 20220.17642
4 Feb 20220.01372
1 Apr 20220.0115
7 Mar 20230.00134
3 Apr 20230.00131
8 May 20230.00262
1 Jun 20230.00257
28 Jul 20230.00196
1 Apr 20240.00230
27 Apr 20240.00365
11 May 20240.01438
23 May 20240.00413
7 Jun 20240.07365
20 Jun 20240.00716
4 Jul 20240.06023
10 Jul 20240.00054
15 Aug 20240.00062
29 Aug 20240.00049
14 Sep 20240.00051
15 Dec 20240.00056
30 Dec 20240.00053
17 Mar 20250.06063
19 Mar 20250.04827
25 Mar 20250.06272
29 Mar 20250.22577
30 Mar 20250.06272
2 Apr 20250.05862
2 Jul 20250.07136
18 Jul 20250.06173
7 Aug 20250.07136
10 Aug 20250.06173
28 Sep 20250.07081
1 Oct 20250.07513
14 Oct 20250.08013
22 Oct 20250.07361
27 Oct 20250.07969
28 Oct 20250.07361
31 Oct 20250.05888
14 Nov 20250.05972
18 Nov 20250.15112
21 Nov 20250.03076
1 Dec 20250.02995
27 Dec 20250.03259
28 Dec 20250.02995
3 Jan 20260.02878
8 Jan 20260.02257
15 Jan 20260.02429
3 Apr 20260.02335
8 Apr 20260.02767
12 May 20260.02784
15 Jun 20260.14393
24 Jul 20260.15616
11 Aug 20260.21661
8 Sep 20260.21827

56 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt

The full biography

EPSS 0.21827Published2021-08-12CISA KEV2022-03-31Index as of2026-09-08

Listed by CISA 231 days after it published and the record had been public for 5 years when this index was last written.

Published 2021-08-12 receipt · CISA KEV 2022-03-31 receipt · Index as of 2026-09-08 derived

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