CASCACascade Atlas

Evidence dossier

CVE-2021-40450

Win32k Elevation of Privilege Vulnerability

Exploited in the wild (CISA KEV since Apr 25, 2022). microsoft reports CVSS 3.1 7.8. EPSS estimates 2.1% exploit likelihood as of Aug 27, 2026.

68.7–73.3Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Win32k Elevation of Privilege Vulnerability

State
PUBLISHED
Published
Oct 13, 2021
Updated
Oct 21, 2025
Evidence coverage
92%

Evidence chronology

What was known when

Download this view's receipt →
  1. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

    Inspect raw assertion
    Field
    container
    Value
    CISA ADP Vulnrichment
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CVE Program

    Record text: CVE Program Container

    Inspect raw assertion
    Field
    container
    Value
    CVE Program Container
    Original evidence ↗
  3. Source dateSource date omittedFirst observed by CASCA
    microsoft

    Record text: Win32k Elevation of Privilege Vulnerability

    Inspect raw assertion
    Field
    container
    Value
    Win32k Elevation of Privilege Vulnerability
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Microsoft Win32k Privilege Escalation Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Microsoft Win32k Privilege Escalation Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 2.08% probability · 80.09th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.020760000000; percentile 0.800860000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Apr 25, 2022 · first observed Jul 19, 2026

Exploit likelihood2.08%

FIRST EPSS · score date Aug 27, 2026 · 80.1th percentile · first observed Aug 27, 2026

SeverityCVSS 7.8

microsoft · CVSS 3.1 · first observed Jul 19, 2026 · same-version scores align in this snapshot

Evidence detail

Source limits and decisions

Why each evidence state has this value

casca-unknown-reasons-v1
Exploitation statusEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Severity assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 2026
Resolution
None
Affected productsSource-reported scope

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-ADPIndependent enrichment
Record text

CISA ADP Vulnrichment

Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CVE ProgramDerivative copy
Record text

CVE Program Container

Inspect raw assertion
Field
container
Value
CVE Program Container
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
microsoftOriginal assertion
Record text

Win32k Elevation of Privilege Vulnerability

Inspect raw assertion
Field
container
Value
Win32k Elevation of Privilege Vulnerability
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Microsoft Win32k Privilege Escalation Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Microsoft Win32k Privilege Escalation Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

2.08% probability · 80.09th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.020760000000; percentile 0.800860000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
10Underlying assertions
10Canonical products
10Target assertions
0Constraint assertions

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 2026-07-21T06:45:29.809Z27d65b0f-b718-4b4f-bb79-c47c68d09dfa
  • Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z955dae73-7302-438b-aee1-058d7cc5d48e

21 scope groups

microsoft · source assertedMicrosoftWindows 10 Version 1809Direct source scope
Affected: 10.0.0 to before 10.0.17763.2237 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2237", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 1909Direct source scope
Affected: 10.0.0 to before 10.0.18363.1854 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.18363.1854", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 2004Direct source scope
Affected: 10.0.0 to before 10.0.19041.1288 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19041.1288", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 20H2Direct source scope
Affected: 10.0.0 to before 10.0.19042.1288 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1288", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 21H1Direct source scope
Affected: 10.0.0 to before 10.0.19043.1288 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19043.1288", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 11 version 21H2Direct source scope
Affected: 10.0.0 to before 10.0.22000.258 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.22000.258", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server 2019Direct source scope
Affected: 10.0.0 to before 10.0.17763.2237 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2237", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server 2019 (Server Core installation)Direct source scope
Affected: 10.0.0 to before 10.0.17763.2237 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2237", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server 2022Direct source scope
Affected: 10.0.0 to before 10.0.20348.288 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.20348.288", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server version 2004Direct source scope
Affected: 10.0.0 to before 10.0.19041.1288 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19041.1288", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server version 20H2Direct source scope
Affected: 10.0.0 to before 10.0.19042.1288 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1288", "versionType": "custom"}]
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_1809Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.17763.2237)Canonical identity product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 10.0.17763.2237
    Match ID
    d03564d3-788a-4bd7-b717-b3681515a5be
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_1909Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.18363.1854)Canonical identity product-ef5324dcc791e4e872d6c2be0aefa1d7687ca82c3b4ac5d1f72c76cce8395218Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    through excluding 10.0.18363.1854
    Match ID
    2dff53d4-2910-4a58-81df-6ddc01d2c523
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_2004Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19041.1288)Canonical identity product-9b245936275be71b526838fc72ea633d195b35bdd9dfc31bb6df51e7700edeccLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    through excluding 10.0.19041.1288
    Match ID
    c995398e-b786-4ac7-b6d4-790ed8c68f8c
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_20h2Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19042.1288)Canonical identity product-55e90faed8848f3d316cf702d119e83086b6dc5a963d9947a7df1c589f50346dLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    through excluding 10.0.19042.1288
    Match ID
    129b19a3-40d5-48d4-b3ca-8934062e6933
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_21h1Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19043.1288)Canonical identity product-e0c6c3f5c5e95b5b83fbbf719a7de2471749e1ca250bebf19bc7898a937a00edLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    through excluding 10.0.19043.1288
    Match ID
    d78c68ae-c471-4234-b0d0-7e09d2e131ab
NVD CPE · OPERATING SYSTEMmicrosoftwindows_11_21h2Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.22000.258)Canonical identity product-7fe28b5b5b17e017d9554204df059dd619746ffb5c80da87bcbfb1c52720d2f4Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_11_21h2:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 5
    Logic
    OR
    Version bounds
    through excluding 10.0.22000.258
    Match ID
    2ff279c0-02c7-4d60-85e8-9fb89492d738
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2004Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19041.1288)Canonical identity product-571f6df0fa50d71be9551414060ed8bfcdb500437871cf9595b7fa6b034cecbdLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 6
    Logic
    OR
    Version bounds
    through excluding 10.0.19041.1288
    Match ID
    486e7f23-6a3b-46aa-9f31-91edf933b36a
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2019Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.17763.2237)Canonical identity product-25a2932c0bbcb648f7e391c8b9d34c734e5085444c03c1c206b9d4c4baa80b25Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 7
    Logic
    OR
    Version bounds
    through excluding 10.0.17763.2237
    Match ID
    a555704d-bb77-46a3-a0f9-62409fcc5f40
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2022Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.20348.288)Canonical identity product-d196d31962e613955a91e33e795c22dcfa7bf25173abebaca616a6350cce9ce1Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 8
    Logic
    OR
    Version bounds
    through excluding 10.0.20348.288
    Match ID
    6e5f3f99-530d-4065-9133-9c251f89b406
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_20h2Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19042.1288)Canonical identity product-457c0c3b89fb1cf896e8491223eac8b0cb1ea61ce3174f915e4fe1032759d5a2Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 9
    Logic
    OR
    Version bounds
    through excluding 10.0.19042.1288
    Match ID
    224fa1b7-84ef-435f-bbfa-33bd39c32595

Affected-product evidence

Accepted scope and product mapping

10 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-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
ad064211-7a0b-4df8-a2de-1e01a9843044
Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-457c0c3b89fb1cf896e8491223eac8b0cb1ea61ce3174f915e4fe1032759d5a2

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
21489684-ca89-410f-9b6e-31e01a0a5fe5
Mapping establishedEvidence supported

vendor-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
29233b4b-4ab3-44de-aad5-5bdfc07fa91d
Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-571f6df0fa50d71be9551414060ed8bfcdb500437871cf9595b7fa6b034cecbd

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
51670ce8-beaa-45ec-8c0d-9d3e673866cf
Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-7fe28b5b5b17e017d9554204df059dd619746ffb5c80da87bcbfb1c52720d2f4

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
50976bfd-2682-482a-b5d8-7a7ebd8cee31
Mapping establishedEvidence supported

vendor-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
45694b8d-b937-41b9-9a5f-b6a731fd251d
Mapping establishedEvidence supported

vendor-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
61f863e1-f966-4768-95c2-5cd2f97b65d3
Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-d196d31962e613955a91e33e795c22dcfa7bf25173abebaca616a6350cce9ce1

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
fbd22b1d-02ec-49a2-9007-64d6b9e5e776
Mapping establishedEvidence supported

vendor-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
8976302d-b713-4072-986d-8084aad8c66f
Mapping establishedEvidence supported

vendor-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
47585ddb-1950-4f24-9590-3ce7bc20d01c
Source-reported scopeSource-reported scope

Canonical 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
11
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
08aea4c0-3292-4f36-8171-221e654b2fdd145d8f55-3864-4898-a736-ae31808eb1102c92bca1-de79-4db9-83cc-50b62e628da86dea6ae2-a8aa-4ad4-b2a4-064113d7bde6937da9c8-01d6-4638-930a-4df619a8d89b9b978006-f301-4693-aa49-ab12c226768bab0a8165-8954-478a-954f-635d35592439b1a1384a-c6e0-4d00-abd3-f0442de66e02c6020bad-31b6-45c2-9005-b42a5ee7f3d8f1773431-4789-4d7f-ad03-833b1f754d06f68200a2-29dd-457e-a5a2-1b6cedea5dc3

Assessments

CVSS by origin

4.6
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:L/AC:L/Au:N/C:P/I:P/A:P
7.8
NVDCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8
secure@microsoft.comCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8
microsoftCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Direct CVE/CNA normalized decisions

7.8Priority eligible

microsoft

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Validation
Valid match
Recomputed
7.8
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.