# CASCA evidence receipt — CVE-2021-43890

- Generation: `gen-409cbd0c74ff4feb70e4944e6b98ce40`
- As known: 2026-07-21T08:13:17.697275+00:00
- Comparison: gen-56ccdaf914f7b4be95b689ccae7dc20d
- Score policy: public-priority-v1.0.1
- Conflict: present

## Source assertions

- **CISA-ADP** (independent_enrichment): container — CISA ADP Vulnrichment
  - Observed: 2026-07-19T04:27:06.398189+00:00
  - Citation: https://www.cve.org/CVERecord?id=CVE-2021-43890
- **CVE** (derivative_copy): container — CVE Program Container
  - Observed: 2026-07-19T04:27:06.398189+00:00
  - Citation: https://www.cve.org/CVERecord?id=CVE-2021-43890
- **microsoft** (original_assertion): container — Windows AppX Installer Spoofing Vulnerability
  - Observed: 2026-07-19T04:27:06.398189+00:00
  - Citation: https://www.cve.org/CVERecord?id=CVE-2021-43890
- **CISA KEV** (original_assertion): observed_exploitation — Microsoft Windows AppX Installer Spoofing Vulnerability
  - Observed: 2026-07-19T04:54:04.25158+00:00
  - Citation: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- **FIRST EPSS** (original_assertion): model_probability — Probability 0.102950000000; percentile 0.951830000000
  - Observed: 2026-07-19T04:54:35.756809+00:00
  - Citation: https://www.first.org/epss/data_stats.html

## CVSS assessments

- **nvd@nist.gov** (Primary, CVSS 3.1): 7.1 — score eligible
  - Evidence class: nvd_enrichment_exact; source rank: 0
  - Validation: valid_match
  - Vector: `CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H`
- **nvd@nist.gov** (Primary, CVSS 2.0): 6 — score eligible
  - Evidence class: nvd_enrichment_exact; source rank: 0
  - Validation: valid_match
  - Vector: `AV:N/AC:M/Au:S/C:P/I:P/A:P`
- **secure@microsoft.com** (Secondary, CVSS 3.1): 7.1 — score eligible
  - Evidence class: exact_record_cna; source rank: 1
  - Validation: valid_match
  - Vector: `CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H`
- **microsoft** (unknown, CVSS 3.1): 7.1 — display only
  - Evidence class: direct_cve_record_display_only; source rank: not applicable
  - Validation: display-only direct record assessment
  - Vector: `CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`

## Applicability scope

- **Microsoft · App Installer** (direct_source; unknown)
  - Versions: [{"status": "affected", "version": "1.0.0.0", "lessThan": "publication", "versionType": "custom"}]
- **microsoft · app_installer** (vulnerable_target; supported)
  - Versions: Any version (unconstrained) (< 1.11); Any version (unconstrained) (< 1.16)
  - Canonical identity: `product-b44f47d6822461bb83c92c5f9fcf6a4dd8c10263b5300085ddd1c02a4c82990d`
  - Official link states: linked_exact
  - Criterion (linked_exact, vulnerable_target): `cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:*`
  - Criterion (linked_exact, vulnerable_target): `cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:*`
- **microsoft · windows_10_1507** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-9851bd571b8ab08bca589cd73710badfef557d036f0fb7707f694f1c9f597cb4`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_1507:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_1709** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-d059dbfcd39652adfca6d48669484008cb5d4a8b33116c81ee002cd9101904af`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_1709:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_1803** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-5e821ea3746af154a469c180e78b9f4d663edf21461517987eed76740c7910c1`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_1803:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_1809** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_1809:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_1903** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-9868fa1c12254f9aff51c0302ecb2ea1ab1d9ca0547bde09677154b24f8c7c61`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_1903:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_1909** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-ef5324dcc791e4e872d6c2be0aefa1d7687ca82c3b4ac5d1f72c76cce8395218`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_1909:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_2004** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-9b245936275be71b526838fc72ea633d195b35bdd9dfc31bb6df51e7700edecc`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_2004:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_20h2** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-55e90faed8848f3d316cf702d119e83086b6dc5a963d9947a7df1c589f50346d`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_20h2:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_21h1** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-e0c6c3f5c5e95b5b83fbbf719a7de2471749e1ca250bebf19bc7898a937a00ed`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_21h1:-:*:*:*:*:*:*:*`
- **microsoft · windows_10_21h2** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-ec10c9f400f23fdf118887f60fe116ffde4adb76dcf118cdd3a7556fd033da3b`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_10_21h2:-:*:*:*:*:*:*:*`
- **microsoft · windows_11_21h2** (environmental_constraint; constrained)
  - Versions: Version not applicable
  - Canonical identity: `product-7fe28b5b5b17e017d9554204df059dd619746ffb5c80da87bcbfb1c52720d2f4`
  - Official link states: linked_exact
  - Criterion (linked_exact, environmental_constraint): `cpe:2.3:o:microsoft:windows_11_21h2:-:*:*:*:*:*:*:*`

## Identity source boundaries

- **cpe_dictionary**: 1775266 records through 2026-07-21T06:45:29.809553+00:00
  - Run: `27d65b0f-b718-4b4f-bb79-c47c68d09dfa`
- **cpe_match**: 643502 records through 2026-07-21T08:13:17.697275+00:00
  - Run: `955dae73-7302-438b-aee1-058d7cc5d48e`

## Limitations and unknowns

- 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; unresolved scope remains unknown.
- NVD-carried upstream facts remain derivative and are not independent corroboration.
- 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.
- Factor D remains unknown because WC-03 has not converted canonical CPE mappings into generation-bound mapping obligations; canonical identity alone does not score applicability.
- Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.

Generated from CASCA normalized evidence. This receipt is not proof that an asset is affected, unaffected, safe, or fixed.