VulnTideExploited vulnerabilities, by vendor. Data as of .
Known exploitedIn CISA's KEV catalog since Ransomware use: known
Microsoft Office

CVE-2021-38646: Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 194 days after the CVE record was published.

How likely is exploitation in the next 30 days?
8%

EPSS score, percentile 94.7 of all scored records

How severe?
7.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline . Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected

  • 16.0.1
  • from 15.0.0 to before 5381.1000
  • from 16.0.0 to before 5215.1000
  • 19.0.0

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: .

Advisories and patches

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Microsoft Microsoft 365 Apps for Enterprise
StatusVersions
Affected16.0.1
Microsoft Microsoft Office 2013 Service Pack 1
StatusVersions
Affectedfrom 15.0.0 to before 5381.1000
Microsoft Microsoft Office 2016
StatusVersions
Affectedfrom 16.0.0 to before 5215.1000
Microsoft Microsoft Office 2019
StatusVersions
Affected19.0.0

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

About this vulnerability

Microsoft Office Access Connectivity Engine contains an unspecified vulnerability which can allow for remote code execution.

Summary: CISA's KEV catalog, as of .

  • CISA added CVE-2021-38646 to its Known Exploited Vulnerabilities (KEV) catalog on 28 Mar 2022.
  • CISA marks it as known to be used in ransomware campaigns.
  • The due date CISA sets for the required action is 18 Apr 2022.
  • The CVE record was published on 15 Sep 2021, 194 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 7.8 (High), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 8% (percentile 94.7), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.

Description

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

Timeline

DateEvent
CVE record published
Added to CISA KEV
CISA due date for the required action
CVE record last updated

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