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CVE-2021-34480

INDEX BUILT · 2026-09-20

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Scripting Engine Memory Corruption Vulnerability

CVE-2021-344804 of 4 sources documented this
32

rank 32 = 8 + 17 + 0 + 7 + 0

rank@v1 · scheduled

Someone is already using it

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

EPSS 0.33947  ·  without this subject the record ranks 24

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 6.8, from NVD  ·  without this subject the record ranks 15

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 32

How much of the world it touches

NVD CPE configurations

8 products in the CPE ranges  ·  without this subject the record ranks 25

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 32

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$1.49Mover the next 30 days, if this record is yours
Movement-$512,000on 2023-12-29, the last material move, 2 years, 8 months before this reading
Basisassumeda published average, not your estate

$1.49M = $4.99M incident cost x 0.8814887365328109 exposure x 0.33947 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

0.33947EPSSNOT IN KEVas of 2026-09-20
Severity6.8 MEDIUMreceipt
Harmpartial impactreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementrisenreceipt
PLATEAU10Minimal movement since 2026-06-15, 75 days at 0.34, as of 2026-08-29. arc-rules@v1

Foresight · where to check next

MicrosoftMicrosoftGoogle ChromePHPIvanti Connect34480

This record is one instance of CWE-787, out-of-bounds write. The index holds 14893 prior instances of this class, 164 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.

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

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Reachnetwork-reachable · no privileges required · user interaction required · high attack complexityreceipt
ImpactComplete confidentiality and integrity lossreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classCWE-787 Out-of-bounds Writereceipt
Published consequencesCWE-787: Integrity: Modify Memory, Execute Unauthorized Code or Commands; Availability: DoS: Crash, Exit, or Restart; Other: Unexpected State[email protected]

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.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

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

Authority who says so

CVSS, the CNA6.8 MEDIUMreceipt
CVSS, NVD6.8 MEDIUMreceipt
Exploit probability0.33947 · top 2% of all CVEsreceipt
Blast breadth2 products across 1 vendorderived
Assigned bymicrosoftreceipt
Recorded changes63 · 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 20h2; microsoft windows 10 21h1; microsoft windows 10 1607; microsoft windows 10 1809receipt
Show all 8 published ranges
microsoft windows 10 20h2
microsoft windows 10 21h1
microsoft windows 10 1607
microsoft windows 10 1809
microsoft windows 10 1909
microsoft windows 10 2004
microsoft windows server 2008 r2
microsoft windows server 2012 r2
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

Scripting Engine Memory Corruption Vulnerability receipt

NVD's analysis a second authority

severity
6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P
weakness
CWE-787
affected versions
microsoft windows 10 20h2; microsoft windows 10 21h1; microsoft windows 10 1607; and 5 more, listed in full below
also scored by
[email protected] 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N · [email protected] 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

check it yourself msrc.microsoft.com receipt

Dated events

2022-01-06EPSS moved 0.06 to 0.212023-03-07EPSS moved 0.03 to 0.812026-08-29EPSS moved 0.40 to 0.34

Movement the material steps

13 Aug 20210.0034
6 Jan 20220.20821 · crossed 0.10
4 Feb 20220.09498 · crossed 0.10
7 Mar 20230.81364 · crossed 0.10 and 0.50 · scoring model v2023.03.01
2 May 20230.60444
1 Jun 20230.48531 · crossed 0.50
15 Jun 20230.59970 · crossed 0.50
26 Aug 20230.78570
6 Oct 20230.60474
29 Dec 20230.48158 · crossed 0.50
12 Jan 20240.35598
23 May 20240.18489
7 Jun 20240.35064
17 Dec 20240.11457
17 Mar 20250.03344 · crossed 0.10 · scoring model v2025.03.14
15 Jun 20260.31825 · crossed 0.10 · scoring model v2026.06.15
29 Aug 20260.33947
Show all 63 observations
13 Aug 20210.0034
24 Aug 20210.0375
10 Sep 20210.05536
6 Jan 20220.20821
4 Feb 20220.09498
1 Apr 20220.02861
28 Feb 20230.03102
7 Mar 20230.81364
3 Apr 20230.71949
2 May 20230.60444
8 May 20230.56167
1 Jun 20230.48531
15 Jun 20230.59970
12 Jul 20230.67644
28 Jul 20230.64582
9 Aug 20230.69757
26 Aug 20230.78570
8 Sep 20230.77568
22 Sep 20230.73096
6 Oct 20230.60474
20 Oct 20230.57628
4 Nov 20230.62096
16 Nov 20230.60867
14 Dec 20230.59798
29 Dec 20230.48158
12 Jan 20240.35598
25 Jan 20240.42629
21 Feb 20240.42757
18 Mar 20240.28182
1 Apr 20240.32182
14 Apr 20240.37113
27 Apr 20240.33048
11 May 20240.37740
23 May 20240.18489
7 Jun 20240.35064
4 Jul 20240.42626
18 Jul 20240.41296
31 Jul 20240.33808
28 Sep 20240.31682
29 Oct 20240.34511
28 Nov 20240.31682
17 Dec 20240.11457
15 Jan 20250.11655
17 Mar 20250.03344
19 Mar 20250.02489
29 Mar 20250.08407
30 Mar 20250.02489
16 Apr 20250.01829
3 Jun 20250.01736
1 Oct 20250.01667
27 Oct 20250.01736
28 Oct 20250.01667
4 Nov 20250.02247
18 Nov 20250.05516
21 Nov 20250.02247
10 Dec 20250.02358
13 Dec 20250.02597
27 Dec 20250.02364
28 Dec 20250.02271
3 Jan 20260.03053
15 Jun 20260.31825
11 Aug 20260.39782
29 Aug 20260.33947

63 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 0.33947Published2021-08-12Index as of2026-08-29

The record had been public for 5 years when this index was last written.

Published 2021-08-12 receipt · Index as of 2026-08-29 derived

The pattern, elsewhere

This record is one instance of CWE-787, out-of-bounds write. The index holds 14893 prior instances of this class, 164 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]

CVE-2020-0968 · Microsoft Internet Explorer 9matches 8 of 9KEV listed · 2020receipt
CVE-2019-1367 · Microsoft Internet Explorer 9matches 8 of 9KEV listed · 2019receipt
CVE-2020-0878 · Microsoft ChakraCorematches 7 of 9KEV listed · 2020receipt
CVE-2022-2294 · Google Chromematches 6 of 9KEV listed · 2022receipt
CVE-2019-11043 · PHPmatches 6 of 9KEV listed · 2019receipt
CVE-2025-0282 · Ivanti Connect Securematches 5 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

14893 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.

Siblings and hubs

Records related to this one

Its defect family

microsoft windows 10 version 1507

Of the 9 records in this family, this is the only one holding a stated fix version: 10.0.10240.19022; 10.0.14393.4583; 10.0.17763.2114; 10.0.183.

Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.

Family membership: held values

This record is one of a group, and the group's page describes all of them. This page is kept and dated, and the defect family's own page is the one we offer for indexing: the whole group.

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What usually comes next

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