Home/CVE/Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
CVE

CVE-2021-38646

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability.

HIGH · CVSS 7.8 ⚠ CISA KEV EPSS 0.50932 Ransomware: known
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  • Listed on CISA KEV (known exploited in the wild)
  • Linked to known ransomware campaigns
  • SSVC exploitation status: active
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 2% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules8 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

▤

Affected Products & Versions

2
microsoft 365 appsall versions
microsoft officeall versions
◈

Sigma Hunt Rules

8
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSuspicious Microsoft Office Child Process - MacOS
producthighCode Executed Via Office Add-in XLL File
producthighPotential Persistence Via Microsoft Office Add-In
producthighPotential Persistence Via Microsoft Office Startup Folder
producthighFile With Uncommon Extension Created By An Office Application
producthighOffice Macro File Creation From Suspicious Process
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Scoring & Timeline

7.8
HIGH · CVSS v3.1 · secure@microsoft.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD15 Sep 2021 · 12:15 PM
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
cisaKEV-CVE-2021-38646
msrcCVE-2021-38646Remote Code Execution
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-38646PatchVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-38646US Government Resource
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