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CVE-2021-34486

INDEX BUILT · 2026-09-20

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Windows Event Tracing Elevation of Privilege Vulnerability

CVE-2021-344864 of 4 sources documented this
67

rank 67 = 40 + 12 + 2 + 7 + 6

rank@v1 · this cycle

Someone is already using it

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

EPSS 0.09253 · CISA KEV listed  ·  without this subject the record ranks 27

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 55

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

rose on 2025-09-28  ·  without this subject the record ranks 65

How much of the world it touches

NVD CPE configurations

8 products in the CPE ranges  ·  without this subject the record ranks 60

Someone else already set the date

CISA KEV remediation due date

CISA remediation date held  ·  without this subject the record ranks 61

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$462,000over the next 30 days, if this record is yours
Movement+$397,000on 2025-03-19, the last material move, 1 year, 5 months before this reading
Basisassumeda published average, not your estate

$462,000 = $4.99M incident cost x 1 exposure x 0.09253 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

0.09253EPSSKEV · LISTED
Severity7.8 HIGHreceipt
Harmtotal lossreceipt
Exploitationin the wild · KEVreceipt
Defensefix version namedreceipt
Movementrisenreceipt
PLATEAU10Minimal movement since 2026-06-15, 81 days at 0.09, as of 2026-09-04. arc-rules@v1

Foresight · where to check next

Microsoft WindowsMicrosoft WindowsMicrosoft Windows34486

This record is one instance of CWE-416, use after free. The index holds 8701 prior instances of this class, 106 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1

Full pattern panel

Prior records in this weakness class. Each is its own record, dated and receipted.
Color is a claim, not decoration:the hostile worldthe defenseno signalspoke length is how much of the record matches, not how bad it is

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

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Harm, if it fires from the vector and the weakness

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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 classCWE-416 Use After Freereceipt
Published consequencesCWE-416: Integrity: Modify Memory; Availability: DoS: Crash, Exit, or Restart; Confidentiality: Read Memory; Integrity, Confidentiality, Availability: Execute Unauthorized Code or Commands[email protected]
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 in10.0.17763.2114; 10.0.18363.1734; 10.0.19041.1165; 10.0.19042.1165; 10.0.19043.1165receipt
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 2022-04-18receipt
CISA required actionApply updates per vendor instructions.receipt
Published to CISA KEV228 daysderived

Exploit Status & Known PoCs a ladder, not a score

Current rung: Exploited in the wild · CISA KEV listed, 2022-03-28.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published · 2 public repositories2021-10-12receipt
  • RUNG 3Exploited in the wild · CISA KEV listed2022-03-28receipt
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA7.8 HIGHreceipt
CVSS, NVD4.6 MEDIUMreceipt
Exploit probability0.09253 · top 5% of all CVEsreceipt
Blast breadth3 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes74 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productMicrosoft Windows 10 Version 1809; Microsoft Windows 10 Version 1909; Microsoft Windows 10 Version 2004; Microsoft Windows 10 Version 20H2; Microsoft Windows 10 Version 21H1…receipt
Published rangesmicrosoft 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 < 10.0.19042.1165receipt
Show all 8 published ranges
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 2019 < 10.0.17763.2114
microsoft windows server 20h2 < 10.0.19042.1165
Fixed in10.0.17763.2114; 10.0.18363.1734; 10.0.19041.1165; 10.0.19042.1165; 10.0.19043.1165receipt

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 Event Tracing 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
weakness
CWE-416
affected versions
microsoft windows 10 1809 < 10.0.17763.2114; microsoft windows 10 1909 < 10.0.18363.1734; microsoft windows 10 2004 < 10.0.19041.1165; and 5 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

2021-10-12EPSS moved 0.05 to 0.182022-03-28Added to CISA KEV2022-04-18CISA remediation due2026-06-15EPSS moved 0.36 to 0.07

Movement the material steps

13 Aug 20210.00416
12 Oct 20210.17642 · crossed 0.10
4 Feb 20220.01372 · crossed 0.10
7 Mar 20230.01593 · scoring model v2023.03.01
7 Jun 20240.16529 · crossed 0.10
20 Jun 20240.01285 · crossed 0.10
4 Jul 20240.18195 · crossed 0.10
18 Jul 20240.00706 · crossed 0.10
17 Mar 20250.09801 · scoring model v2025.03.14
19 Mar 20250.1775 · crossed 0.10
29 Jun 20250.28855
20 Oct 20250.41829
18 Nov 20250.30981
15 Jun 20260.07428 · crossed 0.10 · scoring model v2026.06.15
11 Aug 20260.09253
Show all 60 observations
13 Aug 20210.00416
24 Aug 20210.04557
12 Oct 20210.17642
4 Feb 20220.01372
7 Mar 20230.01593
3 Apr 20230.01275
17 Apr 20230.01158
1 Jun 20230.00933
12 Jul 20230.00729
28 Jul 20230.00558
29 Dec 20230.00261
1 Apr 20240.00306
27 Apr 20240.00584
11 May 20240.02776
23 May 20240.00673
7 Jun 20240.16529
20 Jun 20240.01285
4 Jul 20240.18195
18 Jul 20240.00706
15 Aug 20240.08925
29 Aug 20240.00638
14 Sep 20240.02791
28 Sep 20240.00357
13 Oct 20240.00885
29 Oct 20240.00575
13 Nov 20240.00728
28 Nov 20240.00488
15 Dec 20240.03357
30 Dec 20240.00325
1 Feb 20250.00566
19 Feb 20250.06021
9 Mar 20250.09970
17 Mar 20250.09801
19 Mar 20250.1775
20 Mar 20250.15066
23 Mar 20250.1775
24 Mar 20250.15066
25 Mar 20250.26094
27 Mar 20250.26504
28 Mar 20250.27685
29 Mar 20250.26504
30 Mar 20250.27685
29 Jun 20250.28855
23 Aug 20250.28444
28 Sep 20250.38765
20 Oct 20250.41829
22 Oct 20250.45233
31 Oct 20250.42487
4 Nov 20250.3699
17 Nov 20250.37064
18 Nov 20250.30981
21 Nov 20250.37064
3 Jan 20260.34654
17 Mar 20260.34278
3 Apr 20260.34372
13 Apr 20260.36471
12 May 20260.35587
31 May 20260.36467
15 Jun 20260.07428
11 Aug 20260.09253

60 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 0.09253Published2021-08-12Public PoC2021-10-12CISA KEV2022-03-28Index as of2026-09-04

Listed by CISA 228 days after it published and the record had been public for 5 years when this index was last written.

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

Published 2021-08-12 receipt · Public PoC 2021-10-12 receipt · CISA KEV 2022-03-28 receipt · Index as of 2026-09-04 derived

The pattern, elsewhere

This record is one instance of CWE-416, use after free. The index holds 8701 prior instances of this class, 106 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]

CVE-2025-29824 · Microsoft Windows 10 Version 1507matches 9 of 9KEV listed · 2025receipt
CVE-2021-40449 · Microsoft Windows 10 Version 1809matches 9 of 9KEV listed · 2021receipt
CVE-2025-21334 · Microsoft Windows 10 Version 21H2matches 9 of 9KEV listed · 2025receipt
CVE-2025-21335 · Microsoft Windows 10 Version 21H2matches 9 of 9KEV listed · 2025receipt
CVE-2025-30400 · Microsoft Windows 10 Version 1809matches 9 of 9KEV listed · 2025receipt
CVE-2025-32701 · Microsoft Windows 10 Version 1507matches 9 of 9KEV listed · 2025receipt

"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1

8701 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.

No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.

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What usually comes next

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