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High 7.8Known exploited (CISA KEV)Published Sep 15, 2021
CVE-2021-38646Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
Updated under an hour ago ()
Does this affect you?
It affects Microsoft 365 Apps for Enterprise and 5 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Mar 28, 2022; federal agencies had to remediate by Apr 18, 2022, and it is known to be used in ransomware. Treat that date as your deadline.
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Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
- CVSS
- 7.8 HIGH (v3.1, CNA)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
- Weakness (CWE)
- Not given
- Known exploited
- Added to CISA KEV Mar 28, 2022; federal remediation due Apr 18, 2022; known ransomware useApply updates per vendor instructions.
- EPSS (exploitation in the next 30 days)
- 7.99% (percentile 95)
- Assigned by
- microsoft
- NVD analysis
- Analyzed
- Record last updated
- Aug 10, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Microsoft Microsoft 365 Apps for Enterprise microsoft:365_apps_for_enterprise (from the name) | from 16.0.1 before https://aka.ms/OfficeSecurityReleases | CNA record |
Microsoft Microsoft Office 2013 Service Pack 1 microsoft:office_2013_service_pack_1 (from the name) | from 15.0.0 before 5381.1000 | CNA record |
Microsoft Microsoft Office 2016 microsoft:office_2016 (from the name) | from 16.0.0 before 5215.1000 | CNA record |
Microsoft Microsoft Office 2019 microsoft:office_2019 (from the name) | from 19.0.0 before https://aka.ms/OfficeSecurityReleases | CNA record |
microsoft 365_apps microsoft:365_apps | all versions | NVD |
microsoft office microsoft:office | 2013; 2013 | NVD |
microsoft office_2016 microsoft:office_2016 | all versions; all versions | NVD |
microsoft office_2019 microsoft:office_2019 | all versions | NVD |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38646vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-38646patch, vendor-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-38646us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.