CASCACascade Atlas

Evidence dossier

CVE-2021-38646

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Exploited in the wild (CISA KEV since Mar 28, 2022). microsoft reports CVSS 3.1 7.8. EPSS estimates 8.0% exploit likelihood as of Aug 27, 2026.

68.7–72.3Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

State
PUBLISHED
Published
Sep 15, 2021
Updated
Oct 21, 2025
Evidence coverage
93%

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: Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

    Inspect raw assertion
    Field
    container
    Value
    Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 7.99% probability · 94.33th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.079870000000; percentile 0.943260000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Mar 28, 2022 · first observed Jul 19, 2026

Exploit likelihood7.99%

FIRST EPSS · score date Aug 27, 2026 · 94.3th 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

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Inspect raw assertion
Field
container
Value
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

7.99% probability · 94.33th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.079870000000; percentile 0.943260000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
5Underlying assertions
2Canonical products
5Target 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

6 scope groups

microsoft · source assertedMicrosoftMicrosoft 365 Apps for EnterpriseDirect source scope
Affected: 16.0.1 to before https://aka.ms/OfficeSecurityReleases (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "16.0.1", "lessThan": "https://aka.ms/OfficeSecurityReleases", "versionType": "custom"}]
microsoft · source assertedMicrosoftMicrosoft Office 2013 Service Pack 1Direct source scope
Affected: 15.0.0 to before 5381.1000 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "15.0.0", "lessThan": "5381.1000", "versionType": "custom"}]
microsoft · source assertedMicrosoftMicrosoft Office 2016Direct source scope
Affected: 16.0.0 to before 5215.1000 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "16.0.0", "lessThan": "5215.1000", "versionType": "custom"}]
microsoft · source assertedMicrosoftMicrosoft Office 2019Direct source scope
Affected: 19.0.0 to before https://aka.ms/OfficeSecurityReleases (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "19.0.0", "lessThan": "https://aka.ms/OfficeSecurityReleases", "versionType": "custom"}]
NVD CPE · APPLICATIONmicrosoft365_appsVulnerable target · 1 assertions
Version not applicableCanonical identity product-14a59f3c1c4fc4cec4da9e1d602ac339da114e67c884352e121c41fb03b7a712Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    40c15edd-98d4-4d06-ba06-21ae0f33c72d
NVD CPE · APPLICATIONmicrosoftofficeVulnerable target · 4 assertions
Version 2013; Version 2016; Version 2019Canonical identity product-f4efee17050cd92d62299077c43827052b373ddcb783c02caa43c2fbb378d2f4Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    ff177984-a906-43fa-bf60-298133fbbd6b
  2. cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    e0b3b0bc-c7c6-4687-ad72-dca29ff9ae3a
  3. cpe:2.3:a:microsoft:office:2013:sp1:*:*:rt:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    f7ddffb8-2337-4dd7-8120-56cc8ef134b4
  4. cpe:2.3:a:microsoft:office:2013:sp1:*:*:-:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    552e1557-d6fa-45dd-9b52-e13acdbb8a62

Affected-product evidence

Accepted scope and product mapping

2 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-14a59f3c1c4fc4cec4da9e1d602ac339da114e67c884352e121c41fb03b7a712

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
a409bb7e-7347-4699-a7df-5a9158a6ad15
Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-f4efee17050cd92d62299077c43827052b373ddcb783c02caa43c2fbb378d2f4

Source class
Nvd cpe vulnerable target
Assertions
4
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
46351399-0fe0-45b3-a25b-8a51960f128b74fd4e81-8fa7-45f4-9674-82bc1bdc89da88ca526f-af89-48c1-89dc-1d459ec0b8e8f45ec457-7c48-463c-96f0-888f2cc9fec8
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
4
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
4f392d69-8190-418f-9ab2-5ef9efdc157c57e189a1-7bfa-4848-b628-45cbe4032e5b9532d7e3-d799-4a9d-a27c-dc29e47dca94a776b0ec-aa4a-46c1-9c5e-ad7bb0b6655e

Assessments

CVSS by origin

6.8
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:N/AC:M/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:N/UI:R/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:N/UI:R/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:N/UI:R/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:N/UI:R/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.