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CVE-2021-33771

INDEX BUILT · 2026-09-20

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Windows Kernel Elevation of Privilege Vulnerability

CVE-2021-337714 of 4 sources documented this
73

rank 73 = 40 + 18 + 1 + 8 + 6

rank@v1 · act now

Someone is already using it

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

EPSS 0.10172 · CISA KEV listed  ·  without this subject the record ranks 33

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 7.2, from NVD  ·  without this subject the record ranks 55

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

rose on 2025-10-31  ·  without this subject the record ranks 72

How much of the world it touches

NVD CPE configurations

11 products in the CPE ranges  ·  without this subject the record ranks 65

Someone else already set the date

CISA KEV remediation due date

CISA remediation date held  ·  without this subject the record ranks 67

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$508,000over the next 30 days, if this record is yours
Movement+$195,000on 2026-08-11, the last material move, 24 days before this reading
Basisassumeda published average, not your estate

$508,000 = $4.99M incident cost x 1 exposure x 0.10172 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

0.10172EPSSKEV · LISTED
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationin the wild · KEVreceipt
Defensefix version namedreceipt
Movementthreshold crossedreceipt
PLATEAU10Minimal movement since 2025-03-17, 536 days at 0.10, as of 2026-09-04. 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
NVD7.2 HIGHreceipt
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.

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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 in10.0.10240.19003; 10.0.14393.4530; 10.0.17763.2061; 10.0.18363.1679; 10.0.19041.1110; 10.0.19042.1110; 10.0.19043.1110; 6.3.9600.20069receipt
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 2021-11-17receipt
CISA required actionApply updates per vendor instructions.receipt
Published to CISA KEV112 daysderived

Exploit Status & Known PoCs a ladder, not a score

Current rung: Exploited in the wild · CISA KEV listed, 2021-11-03.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed2021-11-03receipt
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA7.8 HIGHreceipt
CVSS, NVD7.2 HIGHreceipt
Exploit probability0.10172 · top 5% of all CVEsreceipt
Blast breadth3 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes72 · 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 < 10.0.10240.19003; microsoft windows 10 1607 < 10.0.14393.4530; microsoft windows 10 1809 < 10.0.17763.2061; microsoft windows 10 1909 < 10.0.18363.1679receipt
Show all 11 published ranges
microsoft windows 10 1507 < 10.0.10240.19003
microsoft windows 10 1607 < 10.0.14393.4530
microsoft windows 10 1809 < 10.0.17763.2061
microsoft windows 10 1909 < 10.0.18363.1679
microsoft windows 10 2004 < 10.0.19041.1110
microsoft windows 10 20h2 < 10.0.19042.1110
microsoft windows 10 21h1 < 10.0.19043.1110
microsoft windows server 2004 < 10.0.19041.1110
microsoft windows server 2016 < 10.0.14393.4530
microsoft windows server 2019 < 10.0.17763.2061
microsoft windows server 20h2 < 10.0.19042.1110
Fixed in10.0.10240.19003; 10.0.14393.4530; 10.0.17763.2061; 10.0.18363.1679; 10.0.19041.1110; 10.0.19042.1110; 10.0.19043.1110; 6.3.9600.20069receipt

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 Kernel Elevation of Privilege Vulnerability receipt

NVD's analysis a second authority

severity
7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C
affected versions
microsoft windows 10 1507 < 10.0.10240.19003; microsoft windows 10 1607 < 10.0.14393.4530; microsoft windows 10 1809 < 10.0.17763.2061; and 8 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 7.2. Both are shown because both were published; we do not pick one.

check it yourself msrc.microsoft.com receipt

Dated events

2021-11-03Added to CISA KEV2021-11-17CISA remediation due2022-01-06EPSS moved 0.05 to 0.182022-02-04EPSS moved 0.18 to 0.012026-08-11EPSS moved 0.06 to 0.10

Movement the material steps

15 Jul 20210.00416
6 Jan 20220.17642 · crossed 0.10
4 Feb 20220.01372 · crossed 0.10
7 Mar 20234.9e-4 · scoring model v2023.03.01
17 Mar 20250.0134 · scoring model v2025.03.14
24 Dec 20250.10647 · crossed 0.10
9 Feb 20260.09173 · crossed 0.10
15 Jun 20260.06204 · scoring model v2026.06.15
11 Aug 20260.10172 · crossed 0.10

This score more than doubled inside 72 hours. Both observations are in the full history below.

Show all 61 observations
15 Jul 20210.00416
17 Jul 20210.04557
6 Jan 20220.17642
4 Feb 20220.01372
1 Apr 20220.0115
7 Mar 20234.9e-4
8 Mar 20230.00049
13 Jun 20230.00043
29 Dec 20230.00068
3 Mar 20240.00080
29 Mar 20240.00121
12 Apr 20240.00406
24 Apr 20240.00130
9 May 20240.02421
22 May 20240.00183
5 Jun 20240.01940
19 Jun 20240.00109
17 Jul 20240.00842
31 Jul 20240.00115
16 Aug 20240.00519
30 Aug 20240.00086
14 Sep 20240.00135
30 Sep 20240.00110
15 Oct 20240.00140
30 Oct 20240.00108
16 Nov 20240.00416
2 Dec 20240.00071
3 Jan 20250.00124
21 Jan 20250.00538
8 Feb 20250.00741
8 Mar 20250.00042
17 Mar 20250.0134
29 Mar 20250.02315
30 Mar 20250.0134
15 Apr 20250.01557
25 Jun 20250.01793
30 Jun 20250.0195
15 Jul 20250.01694
29 Jul 20250.01572
12 Aug 20250.01807
13 Sep 20250.00754
17 Oct 20250.01326
21 Oct 20250.00813
22 Oct 20250.01575
30 Oct 20250.04064
31 Oct 20250.09882
18 Nov 20250.07893
21 Nov 20250.09882
24 Dec 20250.10647
27 Dec 20250.13797
28 Dec 20250.10647
9 Feb 20260.09173
5 Mar 20260.07634
17 Mar 20260.06648
8 May 20260.05836
14 May 20260.06826
22 May 20260.06523
4 Jun 20260.06444
15 Jun 20260.06204
6 Jul 20260.06255
11 Aug 20260.10172

61 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 0.10172Published2021-07-14CISA KEV2021-11-03Index as of2026-09-04

Listed by CISA 112 days after it published, exploit probability more than doubled between 2021-07-15 and 2021-07-17 (0.00416 → 0.04557) and the record had been public for 5 years, 1 month when this index was last written.

No material movement in 24 days as of the last ingest this index recorded.

Published 2021-07-14 receipt · CISA KEV 2021-11-03 receipt · Index as of 2026-09-04 derived

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