CASCACascade Atlas

Evidence dossier

CVE-2021-31955

Windows Kernel Information Disclosure Vulnerability

Exploited in the wild (CISA KEV since Nov 3, 2021). microsoft reports CVSS 3.1 5.5. EPSS estimates 81.1% exploit likelihood as of Aug 26, 2026.

77.7–82.0Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Windows Kernel Information Disclosure Vulnerability

State
PUBLISHED
Published
Jun 8, 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: Windows Kernel Information Disclosure Vulnerability

    Inspect raw assertion
    Field
    container
    Value
    Windows Kernel Information Disclosure Vulnerability
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Microsoft Windows Kernel Information Disclosure Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Microsoft Windows Kernel Information Disclosure Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 81.11% probability · 99.6th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.811070000000; percentile 0.996030000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Nov 3, 2021 · first observed Jul 19, 2026

Exploit likelihood81.11%

FIRST EPSS · score date Aug 26, 2026 · 99.6th percentile · first observed Aug 26, 2026

SeverityCVSS 5.5

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

Windows Kernel Information Disclosure Vulnerability

Inspect raw assertion
Field
container
Value
Windows Kernel Information Disclosure Vulnerability
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Microsoft Windows Kernel Information Disclosure Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Microsoft Windows Kernel Information Disclosure Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

81.11% probability · 99.6th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.811070000000; percentile 0.996030000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
8Underlying assertions
8Canonical products
8Target 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

17 scope groups

microsoft · source assertedMicrosoftWindows 10 Version 1809Direct source scope
Affected: 10.0.0 to before 10.0.17763.1999 (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": "10.0.17763.1999", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 1909Direct source scope
Affected: 10.0.0 to before 10.0.18363.1621 (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": "10.0.18363.1621", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 2004Direct source scope
Affected: 10.0.0 to before 10.0.19041.1052 (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": "10.0.19041.1052", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 20H2Direct source scope
Affected: 10.0.0 to before 10.0.19042.1052 (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": "10.0.19042.1052", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows 10 Version 21H1Direct source scope
Affected: 10.0.0 to before 10.0.19043.1052 (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": "10.0.19043.1052", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server 2019Direct source scope
Affected: 10.0.0 to before 10.0.17763.1999 (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": "10.0.17763.1999", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server 2019 (Server Core installation)Direct source scope
Affected: 10.0.0 to before 10.0.17763.1999 (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": "10.0.17763.1999", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server version 2004Direct source scope
Affected: 10.0.0 to before 10.0.19041.1052 (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": "10.0.19041.1052", "versionType": "custom"}]
microsoft · source assertedMicrosoftWindows Server version 20H2Direct source scope
Affected: 10.0.0 to before 10.0.19042.1052 (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": "10.0.19042.1052", "versionType": "custom"}]
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_1809Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.17763.1999)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 10.0.17763.1999
    Match ID
    0df9b75a-049e-44aa-b4dd-3384f3ed5e52
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_1909Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.18363.1621)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 10.0.18363.1621
    Match ID
    25bdc753-1696-4a75-ac79-e482662bd743
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_2004Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19041.1052)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 10.0.19041.1052
    Match ID
    4110ddef-afeb-469c-8ff1-9208d5ad254a
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_20h2Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19042.1052)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 10.0.19042.1052
    Match ID
    a81d1961-6d36-4bbb-96c2-15d5480637ce
NVD CPE · OPERATING SYSTEMmicrosoftwindows_10_21h1Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19043.1052)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 10.0.19043.1052
    Match ID
    579557c6-7d3c-4d9d-b8df-e3193c01715c
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2004Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19041.1052)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 5
    Logic
    OR
    Version bounds
    through excluding 10.0.19041.1052
    Match ID
    854be587-9888-4365-abba-ac951dc7bcb4
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2019Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.17763.1999)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 6
    Logic
    OR
    Version bounds
    through excluding 10.0.17763.1999
    Match ID
    acdf4d88-d052-40a6-96a7-865c33112b4f
NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_20h2Vulnerable target · 1 assertions
Any version (unconstrained) (< 10.0.19042.1052)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 7
    Logic
    OR
    Version bounds
    through excluding 10.0.19042.1052
    Match ID
    b963e9ab-d1f7-45d1-8b7e-675732475401

Affected-product evidence

Accepted scope and product mapping

8 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
ea9c8154-37bf-4a5b-b0f0-f995680b3079
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
09baa615-eeda-4690-a26d-7ef10e87a9bd
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
c5e75361-c920-4f8c-8d14-c3b7e95f3b15
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
add37d96-c780-4ddf-bd4a-6837efa4a4f4
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
21dd05b3-cb4e-4966-864b-2811c8a46472
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
b7b43203-7fa5-40cc-89fb-9ee20ca16ddc
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
0a37a772-8a8c-4d8d-82bd-1102ca7c1177
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
9fca2b06-f437-4fab-b0f1-1dae526a7b4e
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
9
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
2a795784-ed5f-453f-b157-5c58573a0b552fd5c834-4dd8-4115-b2d3-3b26a890d7dc65e58dd0-2a6a-4c9a-9111-ee62190d001a6b576bc5-0407-424a-acca-42e42c2f13af6f785460-b92d-4468-b5f5-be9e8db7ca798312fd19-fe8e-4005-82fa-ec9d30bf0766ba955ca9-4f10-464b-a0b8-d6d4cf6225a3dd917de4-5788-4e85-a293-9d93c5d6d99de2802504-6dcc-42c1-a38f-b653d92583d5

Assessments

CVSS by origin

2.1
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:L/AC:L/Au:N/C:P/I:N/A:N
5.5
NVDCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
5.5
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:N/A:N
5.5
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:N/A:N/E:F/RL:O/RC:C

Direct CVE/CNA normalized decisions

5.5Priority 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:N/A:N/E:F/RL:O/RC:C
Validation
Valid match
Recomputed
5.5
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.