Evidence dossier
CVE-2021-33742
Windows MSHTML Platform Remote Code Execution Vulnerability
Exploited in the wild (CISA KEV since Nov 3, 2021). microsoft reports CVSS 3.1 7.5. Severity assessments differ within at least one CVSS version. EPSS estimates 59.1% exploit likelihood as of Aug 27, 2026.
As of Aug 27, 2026
Normalized restatement
Windows MSHTML Platform Remote Code Execution Vulnerability
- State
- PUBLISHED
- Published
- Jun 8, 2021
- Updated
- Oct 21, 2025
- Evidence coverage
- 79%
Evidence chronology
What was known when
- Source dateSource date omittedFirst observed by CASCACISA-ADPOriginal evidence ↗
Record text: CISA ADP Vulnrichment
Inspect raw assertion
- Field
container- Value
- CISA ADP Vulnrichment
- Source dateSource date omittedFirst observed by CASCACVE ProgramOriginal evidence ↗
Record text: CVE Program Container
Inspect raw assertion
- Field
container- Value
- CVE Program Container
- Source dateSource date omittedFirst observed by CASCAmicrosoftOriginal evidence ↗
Record text: Windows MSHTML Platform Remote Code Execution Vulnerability
Inspect raw assertion
- Field
container- Value
- Windows MSHTML Platform Remote Code Execution Vulnerability
- Source dateFirst observed by CASCACISA KEVOriginal evidence ↗
Exploitation cataloged: Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability
Inspect raw assertion
- Field
observed_exploitation- Value
- Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability
- Source dateFirst observed by CASCAFIRST EPSSOriginal evidence ↗
EPSS score: 59.14% probability · 99.04th percentile
Inspect raw assertion
- Field
model_probability- Value
- Probability 0.591390000000; percentile 0.990430000000
Assessments differ
Values are shown separately by source and CVSS version.
CISA KEV · catalog date Nov 3, 2021 · first observed Jul 19, 2026
FIRST EPSS · score date Aug 27, 2026 · 99th percentile · first observed Aug 27, 2026
microsoft · CVSS 3.1 · first observed Jul 19, 2026 · values shown separately below
Evidence detail
Source limits and decisions
Why each evidence state has this value
casca-unknown-reasons-v1Eligible evidence is present for this bounded claim.
- Revision
- evidence-policy-v1.1.0
- Cutoff
- Aug 27, 2026
- Resolution
- None
Eligible evidence is present for this bounded claim.
- Revision
- evidence-policy-v1.1.0
- Cutoff
- Aug 27, 2026
- Resolution
- None
Eligible assertions materially conflict and remain visible side by side.
- Revision
- casca-direct-cvss-eligibility-v1
- Cutoff
- Aug 27, 2026
- Resolution
- Resolve conflict
The cited source assertion is retained while canonical product linkage remains open.
- Revision
- casca-factor-d-obligations-v1
- Cutoff
- Aug 27, 2026
- Resolution
- Resolve identity
Source comparison
Who said what
CISA ADP Vulnrichment
Inspect raw assertion
- Field
container- Value
- CISA ADP Vulnrichment
CVE Program Container
Inspect raw assertion
- Field
container- Value
- CVE Program Container
Windows MSHTML Platform Remote Code Execution Vulnerability
Inspect raw assertion
- Field
container- Value
- Windows MSHTML Platform Remote Code Execution Vulnerability
Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability
Inspect raw assertion
- Field
observed_exploitation- Value
- Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability
59.14% probability · 99.04th percentile
Inspect raw assertion
- Field
model_probability- Value
- Probability 0.591390000000; percentile 0.990430000000
Applicability
Cited product scope
Grouped from 1 configuration nodes in this exact snapshot. Visual grouping is navigational; asset exposure and root cause require cited evidence.
Identity source boundaries
- Cpe dictionary1,775,266 records · observed through 2026-07-21T06:45:29.809Z
27d65b0f-b718-4b4f-bb79-c47c68d09dfa - Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z
955dae73-7302-438b-aee1-058d7cc5d48e
31 scope groups
Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.10240.18967", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4467", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.1999", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.18363.1621", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19041.1052", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1052", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19043.1052", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25632", "versionType": "custom"}, {"status": "affected", "version": "6.1.0", "lessThan": "publication", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25632", "versionType": "custom"}, {"status": "affected", "version": "6.1.0", "lessThan": "publication", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20045", "versionType": "custom"}, {"status": "affected", "version": "6.3.0", "lessThan": "1.0.0.0", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25632", "versionType": "custom"}, {"status": "affected", "version": "6.1.0", "lessThan": "publication", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21137", "versionType": "custom"}, {"status": "affected", "version": "6.0.0", "lessThan": "publication", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21137", "versionType": "custom"}, {"status": "affected", "version": "6.0.0", "lessThan": "publication", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.2.0", "lessThan": "6.2.9200.23372", "versionType": "custom"}, {"status": "affected", "version": "6.2.0", "lessThan": "1.0.0.0", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20045", "versionType": "custom"}, {"status": "affected", "version": "6.3.0", "lessThan": "1.0.0.0", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4467", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.1999", "versionType": "custom"}]product-9851bd571b8ab08bca589cd73710badfef557d036f0fb7707f694f1c9f597cb4Linked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 0
- Logic
- OR
- Version bounds
- through excluding 10.0.10240.18967
- Match ID
c6d804cc-3d0a-442d-ad15-77779c9168f5
product-740fec3e9838b5eabe76ebe27e4d0d7a4cb2e0ef7e13923300d3d0b51e3fce1cLinked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 1
- Logic
- OR
- Version bounds
- through excluding 10.0.14393.4467
- Match ID
3330a6ec-e638-4760-91f1-bb920acdbb17
product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43Linked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 2
- Logic
- OR
- Version bounds
- through excluding 10.0.17763.1999
- Match ID
0df9b75a-049e-44aa-b4dd-3384f3ed5e52
product-ef5324dcc791e4e872d6c2be0aefa1d7687ca82c3b4ac5d1f72c76cce8395218Linked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 3
- Logic
- OR
- Version bounds
- through excluding 10.0.18363.1621
- Match ID
25bdc753-1696-4a75-ac79-e482662bd743
product-9b245936275be71b526838fc72ea633d195b35bdd9dfc31bb6df51e7700edeccLinked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 4
- Logic
- OR
- Version bounds
- through excluding 10.0.19041.1052
- Match ID
4110ddef-afeb-469c-8ff1-9208d5ad254a
product-55e90faed8848f3d316cf702d119e83086b6dc5a963d9947a7df1c589f50346dLinked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 5
- Logic
- OR
- Version bounds
- through excluding 10.0.19042.1052
- Match ID
a81d1961-6d36-4bbb-96c2-15d5480637ce
product-e0c6c3f5c5e95b5b83fbbf719a7de2471749e1ca250bebf19bc7898a937a00edLinked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 6
- Logic
- OR
- Version bounds
- through excluding 10.0.19043.1052
- Match ID
579557c6-7d3c-4d9d-b8df-e3193c01715c
product-f20a05098a41a238f96b56b817d0482887bb39ad40620198bbe05da10ee02ffcLinked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 7
- Logic
- OR
- Version bounds
- No explicit bounds
- Match ID
c2b1c231-de19-4b8f-a4aa-5b3a65276e46
Affected-product evidence
Accepted scope and product mapping
14 canonical links · 1 source-reported links
vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-02e254d111ce604757a15650ef469f4f8365d6247da82ce3ac2695c3cfc7dc5f
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
d87b1732-ffa7-4667-912a-4264319ffb6bvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-076c7e47c78d9425d54dea0b063ed7cd79e5f9f0bfdb3c9153b8aec4e71a7ad9
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
947a95fb-0fa9-46c3-9099-64497ccbdf99vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-217b1ab3d25f361a639824f86753d418b35aa2a816ee370bb71b5d1dd883d87a
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
87152f57-5b7f-4f90-a113-555c7498f34adcc3d391-c5b1-4133-b45f-782ef6ca3441vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-25a2932c0bbcb648f7e391c8b9d34c734e5085444c03c1c206b9d4c4baa80b25
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
8074cced-7520-4240-858d-d09b7bbb1c35vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-55e90faed8848f3d316cf702d119e83086b6dc5a963d9947a7df1c589f50346d
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
271661d1-256f-4792-8636-f8550fa0b804vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-5a80416e92fed0cddbb3d4f3840218b448dee11159824ad25a0353da566963fe
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
62959ba3-3496-41c3-8485-9e15477937a698d8957f-ca73-42fa-bf86-735113660975vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-740fec3e9838b5eabe76ebe27e4d0d7a4cb2e0ef7e13923300d3d0b51e3fce1c
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
b678cb70-b767-4f5f-93d5-d82e5e8b32a9vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-7e46de82012029583622f69d79b86bc210b5bd25b8cb3bb4468936702b23c4b0
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
49763b1c-1029-4060-b28d-b2d7a0e8db4fvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-9851bd571b8ab08bca589cd73710badfef557d036f0fb7707f694f1c9f597cb4
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
8e14a5d5-03b9-4d5e-b649-1a0a6f00ec33vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-9b245936275be71b526838fc72ea633d195b35bdd9dfc31bb6df51e7700edecc
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
520ff5f7-37e7-47df-a54a-f110ef876154vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
3ab12ad3-73a8-435a-b443-557d8a76883avendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-e0c6c3f5c5e95b5b83fbbf719a7de2471749e1ca250bebf19bc7898a937a00ed
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
6fdb9ea9-8bac-41b4-9089-e2f6c3b4ea76vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-ef5324dcc791e4e872d6c2be0aefa1d7687ca82c3b4ac5d1f72c76cce8395218
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
629348b1-4988-4c86-a3d4-69de41a163c8vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-f20a05098a41a238f96b56b817d0482887bb39ad40620198bbe05da10ee02ffc
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
102db0c6-bf9a-4b3b-86f2-1e261ffd4ddcCanonical linkage remains open; the cited source assertion is retained below.
Vendor specified only by source · Product specified only by source
- Source class
- Direct cve affected
- Assertions
- 17
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
211164be-5f71-41ca-8752-5cd3743cdefd2b345a84-fd56-4203-bcb4-3be127828a7750023b2b-fadb-46fb-bb30-c7c9d1e396a7512aa27e-8f2a-429b-9c8d-0ef296995f6c5a2105ba-20f1-4e14-a867-5d5e99b069f760e442fb-c75d-405b-8620-a33572d7b7ca83f5c7e4-fca3-43c7-95c4-2b73d9fc8bc98ed78141-e662-4336-9ef2-bab9f43c6d3797f8ce04-9b93-4e75-8385-0db4f0486cefa3759704-fb5d-4a65-b5e7-90a9852dd23da881b6ae-7102-4d38-a1cf-b3c0dc43ed1ba98adaa1-5c7a-47c4-acac-20bc2487cab2ab2f2b06-2b56-4b6d-acf5-df038c9d48c3d65f1941-411d-4314-ba05-9efa5aa3b670d76bca81-e4d7-42aa-a803-facbb4908392e5a9ebdd-55fc-4dcf-9c83-24f4365a5c67e5d11549-393f-4d51-a098-eca7f762189bAssessments
CVSS by origin
AV:N/AC:M/Au:N/C:P/I:P/A:PCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:CDirect CVE/CNA normalized decisions
microsoft
CVSS 3.1 · Primary · Original assertion · rank 1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C- Validation
- Valid match
- Recomputed
- 7.5
- Decision reason
- Evidence supported
- Policy
- casca-direct-cvss-eligibility-v1
Assessments are retained side by side under closed precedence. Cascade never averages CVSS.
Evidence boundaries
- KEV membership is authoritative for the catalog, not proof of exposure in any environment.
- EPSS is a dated model probability and not an individual-environment prediction.
- Affected or fixed status applies only to the exact cited product and version scope; remaining scope stays source-scoped.
- NVD-carried upstream facts remain derivative; independent corroboration requires a separately authored source.
- Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
- NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
- Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.
- OSV aggregation and OSV-converted NVD material are not independent corroboration.
- Red Hat facts are vendor assertions for the exact supplied products.
- Nonmembership and not-yet-observed states are not proof of safety.