Is CVE-2021-38646 actively exploited?

Yes. KEV Intelligence tracks CVE-2021-38646 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2021-38646. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2021-38646 affects Microsoft Microsoft 365 Apps for Enterprise and 3 other products. KEV Intelligence lists 4 version rows; examples include 16.0.1 to < https://aka.ms/OfficeSecurityReleases, 15.0.0 to < 5381.1000, and 16.0.0 to < 5215.1000.

Yes. CVE-2021-38646 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2021-38646

Q: What is CVE-2021-38646?

CVE-2021-38646 is an unauthenticated vulnerability affecting Microsoft Microsoft 365 Apps for Enterprise and 3 other products. Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2021-38646 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Microsoft 365 Apps for Enterprise Remote Code Execution

Microsoft / Microsoft 365 Apps for Enterprise · affected before https://aka.ms/OfficeSecurityReleases

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Severity: CVSS 7.8 · High
Confidence: Confirmed
Exploit status: Exploited in the wild
EPSS: 8.0%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-38646 is an unauthenticated vulnerability affecting Microsoft Microsoft 365 Apps for Enterprise and 3 other products. Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

Microsoft / Microsoft 365 Apps for Enterprise affected before https://aka.ms/officesecurityreleases.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Vendor Product Affected Status

Microsoft Microsoft 365 Apps for Enterprise Before https://aka.ms/OfficeSecurityReleases Affected

Microsoft Microsoft Office 2013 Service Pack 1 Before 5381.1000 Affected

Microsoft Microsoft Office 2016 Before 5215.1000 Affected

Microsoft Microsoft Office 2019 Before https://aka.ms/OfficeSecurityReleases Affected

View vendor advisory

Published: 15 Sep 2021
Exploitation Reported: 28 Mar 2022
Attack vector: Local
Complexity: Low
Privileges: None
User interaction: Required

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-38646
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability msrc.microsoft.com · Vendor Advisory https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38646

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 28 Mar 2022

Independent exploitation attestation added to the KEV Intelligence record.

Used in malware

CISA

Recorded 28 Mar 2022

Malware families have been linked to exploitation of this CVE.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source	Added
CISA First	2022-03-28 00:00 UTC
CVE	2026-08-10 15:31 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

7.8 High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

8.0%

All CVSS Scores

CVSS v3.1 7.8 High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v2.0 6.8 Medium

AV:N/AC:M/Au:N/C:P/I:P/A:P

Timeline

From disclosure to observed exploitation

10 Aug 2026
KEV confirmed by CVE

Exploitation attested by an external source
28 Mar 2022
Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
28 Mar 2022
First public exploitation report

Exploit observed in malware
15 Sep 2021
CVE published

Vulnerability disclosed publicly
13 Aug 2021
CVE ID reserved

Identifier reserved by the CNA

Pro API

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Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-38646

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2021-38646",
  "confidence": "Confirmed",
  "cvss_score": 7.8,
  "cvss_estimated": false,
  "epss_score": 0.07987,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

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