Evidence dossier

CVE-2021-31979

Windows Kernel Elevation of Privilege Vulnerability

Exploited in the wild (CISA KEV since Nov 3, 2021). microsoft reports CVSS 3.1 7.8. EPSS estimates 4.5% exploit likelihood as of Oct 22, 2026.

63.8–77.0Priority evidence range

Evidence through Oct 22, 2026, 6:07 PM UTC

As of Oct 22, 2026

Normalized restatement

Windows Kernel Elevation of Privilege Vulnerability

State: PUBLISHED
Published: Jul 14, 2021
Updated: Oct 7, 2026
Evidence coverage: 85%

Evidence chronology

What was known when

Download this view's receipt →

Source dateSep 1, 2026First observed by CASCASep 1, 2026
CISA KEV
Exploitation cataloged: Microsoft Windows Kernel Privilege Escalation Vulnerability
Inspect raw assertion
Field
observed_exploitation
Value
Microsoft Windows Kernel Privilege Escalation Vulnerability
Original evidence ↗
Source dateSource date omittedFirst observed by CASCAOct 8, 2026
CISA-ADP
Record text: CISA ADP Vulnrichment
Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Original evidence ↗
Source dateSource date omittedFirst observed by CASCAOct 8, 2026
CVE Program
Record text: CVE Program Container
Inspect raw assertion
Field
container
Value
CVE Program Container
Original evidence ↗
Source dateSource date omittedFirst observed by CASCAOct 8, 2026
microsoft
Record text: Windows Kernel Elevation of Privilege Vulnerability
Inspect raw assertion
Field
container
Value
Windows Kernel Elevation of Privilege Vulnerability
Original evidence ↗
Source dateOct 22, 2026First observed by CASCAOct 22, 2026
FIRST EPSS
EPSS score: 4.54% probability · 91.53th percentile
Inspect raw assertion
Field
model_probability
Value
Probability 0.045400000000; percentile 0.915270000000
Original evidence ↗

ExploitationCatalog member

CISA KEV · catalog date Nov 3, 2021 · first observed Sep 1, 2026

Exploit likelihood4.54%

FIRST EPSS · score date Oct 22, 2026 · 91.5th percentile · first observed Oct 22, 2026

SeverityCVSS 7.8

microsoft · CVSS 3.1 · first observed Oct 8, 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 statusLast verified source snapshot retained

The last verified source boundary remains in force for this claim.

Revision: evidence-policy-v1.1.0
Cutoff: Oct 22, 2026
Resolution: Review source contract

Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision: evidence-policy-v1.1.0
Cutoff: Oct 22, 2026
Resolution: None

Severity assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision: casca-direct-cvss-eligibility-v1
Cutoff: Oct 22, 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: Oct 22, 2026
Resolution: Resolve identity

Source comparison

Who said what

CISA KEVOriginal assertion

Exploitation cataloged

Microsoft Windows Kernel Privilege Escalation Vulnerability

Inspect raw assertion

Field: observed_exploitation
Value: Microsoft Windows Kernel Privilege Escalation Vulnerability

Source dateSep 1, 2026First observed by CASCASep 1, 2026Original evidence ↗

CISA-ADPIndependent enrichment

Record text

CISA ADP Vulnrichment

Inspect raw assertion

Field: container
Value: CISA ADP Vulnrichment

Source dateSource date omittedFirst observed by CASCAOct 8, 2026Original evidence ↗

CVE ProgramDerivative copy

Record text

CVE Program Container

Inspect raw assertion

Field: container
Value: CVE Program Container

Source dateSource date omittedFirst observed by CASCAOct 8, 2026Original evidence ↗

microsoftOriginal assertion

Record text

Windows Kernel Elevation of Privilege Vulnerability

Inspect raw assertion

Field: container
Value: Windows Kernel Elevation of Privilege Vulnerability

Source dateSource date omittedFirst observed by CASCAOct 8, 2026Original evidence ↗

FIRST EPSSOriginal assertion

EPSS score

4.54% probability · 91.53th percentile

Inspect raw assertion

Field: model_probability
Value: Probability 0.045400000000; percentile 0.915270000000

Source dateOct 22, 2026First observed by CASCAOct 22, 2026Original evidence ↗

Applicability

Cited product scope

Trace impact →

18Underlying assertions

16Canonical products

18Target 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

Search scopeRoleOfficial link state

41 scope groups

microsoft · source assertedMicrosoftWindows 10 Version 1507Direct source scope

Affected: 10.0.10240.0 to before 10.0.10240.19003 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.10240.0", "lessThan": "10.0.10240.19003", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 1607Direct source scope

Affected: 10.0.14393.0 to before 10.0.14393.4530 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.4530", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 1809Direct source scope

Affected: 10.0.17763.0 to before 10.0.17763.2061 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.2061", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 1809Direct source scope

Affected: 10.0.0 to before 10.0.17763.2061 (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": "10.0.17763.2061", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 1909Direct source scope

Affected: 10.0.0 to before 10.0.18363.1679 (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": "10.0.18363.1679", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 2004Direct source scope

Affected: 10.0.0 to before 10.0.19041.1110 (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": "10.0.19041.1110", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 20H2Direct source scope

Affected: 10.0.0 to before 10.0.19042.1110 (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": "10.0.19042.1110", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 10 Version 21H1Direct source scope

Affected: 10.0.0 to before 10.0.19043.1110 (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": "10.0.19043.1110", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 7Direct source scope

Affected: 6.1.0 to before 6.1.7601.25661 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25661", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 7 Service Pack 1Direct source scope

Affected: 6.1.0 to before 6.1.7601.25661 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25661", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows 8.1Direct source scope

Affected: 6.3.0 to before 6.3.9600.20069 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20069", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2008 R2 Service Pack 1Direct source scope

Affected: 6.1.7601.0 to before 6.1.7601.25661 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.1.7601.0", "lessThan": "6.1.7601.25661", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)Direct source scope

Affected: 6.1.7601.0 to before 6.1.7601.25661 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.1.7601.0", "lessThan": "6.1.7601.25661", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2008 Service Pack 2Direct source scope

Affected: 6.0.6003.0 to before 6.0.6003.21167 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.0.6003.0", "lessThan": "6.0.6003.21167", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)Direct source scope

Affected: 6.0.6003.0 to before 6.0.6003.21167 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.0.6003.0", "lessThan": "6.0.6003.21167", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012Direct source scope

Affected: 6.2.9200.0 to before 6.2.9200.23409 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.2.9200.0", "lessThan": "6.2.9200.23409", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012 R2Direct source scope

Affected: 6.3.9600.0 to before 6.3.9600.20069 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.3.9600.0", "lessThan": "6.3.9600.20069", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012 R2 (Server Core installation)Direct source scope

Affected: 6.3.9600.0 to before 6.3.9600.20069 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.3.9600.0", "lessThan": "6.3.9600.20069", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012 (Server Core installation)Direct source scope

Affected: 6.2.9200.0 to before 6.2.9200.23409 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.2.9200.0", "lessThan": "6.2.9200.23409", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2016Direct source scope

Affected: 10.0.14393.0 to before 10.0.14393.4530 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.4530", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2016 (Server Core installation)Direct source scope

Affected: 10.0.14393.0 to before 10.0.14393.4530 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.4530", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2019Direct source scope

Affected: 10.0.17763.0 to before 10.0.17763.2061 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.2061", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2019 (Server Core installation)Direct source scope

Affected: 10.0.17763.0 to before 10.0.17763.2061 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.2061", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server version 2004Direct source scope

Affected: 10.0.0 to before 10.0.19041.1110 (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": "10.0.19041.1110", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server version 20H2Direct source scope

Affected: 10.0.0 to before 10.0.19042.1110 (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": "10.0.19042.1110", "versionType": "custom"}]

Affected-product evidence

Accepted scope and product mapping

0 canonical links · 2 source-reported links

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: 25
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Oct 22, 2026

Retained assertion IDs

17630a2a-c7bd-44fb-b713-89b10dec61a71e79edbc-ad5e-456f-badf-dffbe61c0542205a0c60-2437-4471-94e5-c4b5d911928b2478cbcc-e3f8-437f-ac7c-82c3eaf489d230325ce3-ad11-4f1b-836d-6b7747fa6b463677bdc1-9669-4f82-a6ae-7b21f8c085f938819c79-6d6c-449e-b868-792c1649dcdf3fab4a5a-f0ed-4ffd-9494-d1e9bd52a27e4503593f-eea5-4e2d-b49c-f2d6e9c8fd4658d5bbb9-9123-4dfb-a667-7178887c32586391cacc-c37e-4804-a301-7a37aceb17716b52924c-9ccf-4f69-b9f1-66b638486287849224b2-b7f3-44f4-9ca9-cad192f58e58901832a4-5fcc-4665-bf89-bcbce8e858e390945f32-2d55-4264-8370-ff00b773241c9cea49eb-d959-4783-8109-f978a101cc619e6d43cc-69f4-4e1c-af22-46ff38aa0fdfa60e8461-6ecf-471a-8cf5-70a6cd987bdfa67a3b66-1351-4be0-b1ce-c599435180f1a9e2d810-b7a3-452c-a7c4-04f9cb32f06eba5d8cf0-8b99-4eb3-849c-358e24b7e4f5c992537b-bebf-471b-a887-98de45bf25f2d52ec710-a616-47e5-b2da-3ea1d2dc2c44e68a971d-7ff0-4f3f-864c-0b5b0931fa63e91690b7-1d20-4205-a6c5-1df128b3c115

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: Nvd cpe vulnerable target
Assertions: 18
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Oct 22, 2026

Retained assertion IDs

02ee24f6-aa43-4878-81d2-f572e4a09399030173e6-6474-440e-a0ca-08e36d2f9e190ebe2a96-f092-492e-a1c9-a83c70ceebf220e77e2f-67b3-4276-9d0f-26a939a41612255c761c-8d31-45f8-b5cd-07280d9f60df2d627850-dd83-4d27-9852-fec586c3926d2daba52b-d50c-4f0c-83cf-a5d01d21a5eb3208f601-72e4-40a6-8fc2-860984a5f3b038d31acb-8173-4a84-819b-83409ce318c13f5c1d1d-f4b1-4241-8a84-b8cf3e58f8456484b7c7-8f2f-46a4-80f1-47e45899dc0368f1d4c5-c989-41ad-ba22-9130b441b0c884086ffe-d085-4a37-ad7b-3daae63eba3495775524-5a2d-4e9a-a04c-025bfd5a0ee0a961dbf8-3c2e-43e5-b221-ccc7a78e72a1aa896360-7a7e-4cdf-b90c-0234dc6e65cbd1b674fa-d438-4b91-9cd6-3501a8373c2bd87a1c8a-edd1-4c6e-b621-3cd934b5799c

Assessments

CVSS by origin

7.2

NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:L/AC:L/Au:N/C:C/I:C/A:C

7.8

CVE Program sourceCVSS 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

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:F/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:F/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.