CISA KEV · catalog date Feb 10, 2026 · first observed Sep 1, 2026
Evidence dossier
CVE-2026-21510
Windows Shell Security Feature Bypass Vulnerability
Exploited in the wild (CISA KEV since Feb 10, 2026). microsoft reports CVSS 3.1 8.8. EPSS estimates 24.5% exploit likelihood as of Oct 22, 2026.
As of Oct 22, 2026
Normalized restatement
Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.
- State
- PUBLISHED
- Published
- Feb 10, 2026
- Updated
- Aug 19, 2026
- Evidence coverage
- 92%
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 CASCAmicrosoftOriginal evidence ↗
Record text: Windows Shell Security Feature Bypass Vulnerability
Inspect raw assertion
- Field
container- Value
- Windows Shell Security Feature Bypass Vulnerability
- Source dateFirst observed by CASCACISA KEVOriginal evidence ↗
Exploitation cataloged: Microsoft Windows Shell Protection Mechanism Failure Vulnerability
Inspect raw assertion
- Field
observed_exploitation- Value
- Microsoft Windows Shell Protection Mechanism Failure Vulnerability
- Source dateFirst observed by CASCAFIRST EPSSOriginal evidence ↗
EPSS score: 24.54% probability · 97.88th percentile
Inspect raw assertion
- Field
model_probability- Value
- Probability 0.245370000000; percentile 0.978790000000
FIRST EPSS · score date Oct 22, 2026 · 97.9th percentile · first observed Oct 22, 2026
microsoft · CVSS 3.1 · first observed Aug 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-v1The last verified source boundary remains in force for this claim.
- Revision
- evidence-policy-v1.1.0
- Cutoff
- Oct 22, 2026
- Resolution
- Review source contract
Eligible evidence is present for this bounded claim.
- Revision
- evidence-policy-v1.1.0
- Cutoff
- Oct 22, 2026
- Resolution
- None
Eligible evidence is present for this bounded claim.
- Revision
- casca-direct-cvss-eligibility-v1
- Cutoff
- Oct 22, 2026
- Resolution
- None
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 ADP Vulnrichment
Inspect raw assertion
- Field
container- Value
- CISA ADP Vulnrichment
Windows Shell Security Feature Bypass Vulnerability
Inspect raw assertion
- Field
container- Value
- Windows Shell Security Feature Bypass Vulnerability
Microsoft Windows Shell Protection Mechanism Failure Vulnerability
Inspect raw assertion
- Field
observed_exploitation- Value
- Microsoft Windows Shell Protection Mechanism Failure Vulnerability
24.54% probability · 97.88th percentile
Inspect raw assertion
- Field
model_probability- Value
- Probability 0.245370000000; percentile 0.978790000000
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
35 scope groups
Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.8868", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.8389", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.19044.0", "lessThan": "10.0.19044.6937", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.19045.0", "lessThan": "10.0.19045.6937", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.22631.0", "lessThan": "10.0.22631.6649", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.22631.0", "lessThan": "10.0.22631.6649", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.26100.0", "lessThan": "10.0.26100.7840", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.26200.0", "lessThan": "10.0.26200.7840", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.28000.0", "lessThan": "10.0.28000.1575", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.28000.0", "lessThan": "10.0.28000.1575", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.2.9200.0", "lessThan": "6.2.9200.25923", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.9600.0", "lessThan": "6.3.9600.23022", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.9600.0", "lessThan": "6.3.9600.23022", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.2.9200.0", "lessThan": "6.2.9200.25923", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.8868", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.8868", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.8389", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.8389", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.20348.0", "lessThan": "10.0.20348.4773", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.25398.0", "lessThan": "10.0.25398.2149", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.26100.0", "lessThan": "10.0.26100.32370", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.26100.0", "lessThan": "10.0.26100.32370", "versionType": "custom"}]product-740fec3e9838b5eabe76ebe27e4d0d7a4cb2e0ef7e13923300d3d0b51e3fce1cLinked exactInspect raw assertions
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 0
- Logic
- OR
- Version bounds
- through excluding 10.0.14393.8868
- Match ID
e78a20fd-b910-43df-be89-e971e2fd0049
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 1
- Logic
- OR
- Version bounds
- through excluding 10.0.14393.8868
- Match ID
b941280b-97f6-4f60-80a3-40482a74488d
product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43Linked exactInspect raw assertions
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 2
- Logic
- OR
- Version bounds
- through excluding 10.0.17763.8389
- Match ID
c09c54da-6ab0-4696-a2f2-c11cfc292ea9
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 3
- Logic
- OR
- Version bounds
- through excluding 10.0.17763.8389
- Match ID
369b4e41-3895-4cb7-bd37-d2e4a4d52fb9
product-ec10c9f400f23fdf118887f60fe116ffde4adb76dcf118cdd3a7556fd033da3bLinked exactInspect raw assertions
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 4
- Logic
- OR
- Version bounds
- through excluding 10.0.19044.6937
- Match ID
edb3fd9a-2786-4ec1-8989-2b0d054e0307
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 6
- Logic
- OR
- Version bounds
- through excluding 10.0.19044.6937
- Match ID
37e2bff1-28c0-4fa0-9a6c-020146e4ad54
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 5
- Logic
- OR
- Version bounds
- through excluding 10.0.19044.6937
- Match ID
893dba65-116b-4ae0-80e1-50458cb5fdad
Affected-product evidence
Accepted scope and product mapping
13 canonical links · 1 source-reported links
vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-026201767813843a6d53867bacde4a55c3035cb868c0a72434012c5e30dab148
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
71a50ee3-e260-40db-9803-68717b4a5a62e71a90d5-04c1-4eab-aff6-7b493743896cvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-02e254d111ce604757a15650ef469f4f8365d6247da82ce3ac2695c3cfc7dc5f
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
736b3b5e-325f-4775-be4a-03addbc0452fvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-25a2932c0bbcb648f7e391c8b9d34c734e5085444c03c1c206b9d4c4baa80b25
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
548a3e21-8340-414c-877d-ad8643be105dvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-3fe7da0d567cbba9da3f09deea827ccacd90ac3643fc3e1622f75fb001f24443
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
fc00570b-b3e1-440f-8c86-994427a1afe6vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-5a80416e92fed0cddbb3d4f3840218b448dee11159824ad25a0353da566963fe
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
4ca719d8-8255-425b-94e3-adf546bfcc1f8a832cda-50a2-4d35-8f26-47de9c6f059bvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-740fec3e9838b5eabe76ebe27e4d0d7a4cb2e0ef7e13923300d3d0b51e3fce1c
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
7a8f67a9-4327-4e31-a150-629d27280b24f8c97f5f-4f67-4145-a9b4-080fb934a558vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-8665879a2f5fe8b8eab868c43d6ace340b95d1f3879639d97ebdf60ef7b49b5f
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
7639db9a-4bf2-4d10-abb4-290936eead06a138974b-22da-4ac9-9a0e-e045d04136f2vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
2f505830-a414-4375-9fa2-0bd144ca13957c149794-059c-4c85-a367-294abc7f9da7vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-a6295b9daad3ca57ce70751badba5b7fe99229c8a562cc7400e8cfef3daccaee
- Source class
- Nvd cpe vulnerable target
- Assertions
- 3
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
9d072f8f-c1bc-4261-99f7-841a5e821903be39093a-202c-4b53-ac00-3700e78ad793fadc6d84-1a8c-492b-8005-579d8cf56e94vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-bc66b50eed682b3633d0f3a2914725d0a72d6d0d5fece14f566d91bc87448c0b
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
1ed6cb95-0495-44b5-94f4-54b645337bccvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-d196d31962e613955a91e33e795c22dcfa7bf25173abebaca616a6350cce9ce1
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
1b09c8ca-6e15-4fcf-9b6f-c5a224829993vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-e9349aae7bae97a590ecc61309b626fd2c236f349da7ff6c765ab3d5cefdfa78
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
02c6971e-5848-4ba7-a875-a09c916f904e8f96cf1f-c081-47d1-a4ce-b158a6cb0679vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-ec10c9f400f23fdf118887f60fe116ffde4adb76dcf118cdd3a7556fd033da3b
- Source class
- Nvd cpe vulnerable target
- Assertions
- 3
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
2fae2388-d0b6-4778-836c-778560b5b5e867deecf9-1e4c-40b4-ae26-07ae05f17786d3d5de17-c139-4f01-a540-c8045740c664Canonical 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
- 22
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Oct 22, 2026
Retained assertion IDs
0e1eab1d-d3a6-4098-b180-77a599ed3c2a15ae0549-c7a5-4139-8be1-b755ae1aaf452da3d55c-a362-4c25-9d6b-b588f5cfe0f5325b78c2-4254-4006-8959-c0b15e98ee1e34016bcc-3168-4868-adbc-9a7a96d678c440ae7bac-0e70-4c4c-b708-930155c463b64462b1fa-7b73-4073-a4e9-bb0f8c489adf57ec9403-d3b4-41db-a6d1-ce1272b25ae05e8da921-0766-406d-a0bb-ad586be2e31f62cc5083-27a3-440b-9d6a-ed6b000cccfc63727d16-485d-4a38-90f2-e4a6f8cb1a1f78d1b3f6-b564-4735-a47c-b6a33aae65f28dbaa670-0931-40d6-9be6-dc935dca53fea14ef4cc-9053-4ebc-8462-8a3e51be7f60bff0767b-625b-4ecf-a392-d4f47a7f2d05c1e42c3b-2d81-4b36-a62c-cef1215cd97fda1cb2db-96df-4234-9a75-f5a3d1139225de7ab188-07fc-4ab3-a350-e5bedc8bcbc5e25c3c2b-8757-4ac2-9348-367e9bdaf5aaf39e7cd3-26e9-48e1-8ca5-1d6985b83732f6ff96c8-8756-4690-85e3-98b1bae3e350f7c5eaaa-661e-40f7-ad16-4d3bc10612ebAssessments
CVSS by origin
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HCVSS:3.1/AV:N/AC:L/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:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C- Validation
- Valid match
- Recomputed
- 8.8
- 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.