CVE-2021-38646
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 18 April 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 7.99% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 28 March 2022 · due 18 April 2022 · used in ransomware campaigns
- Affected
- microsoft/365 apps · microsoft/office · microsoft/office 2016 · microsoft/office 2019
- Source
- secure@microsoft.com
EPSS 8.0% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-38646
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38646Patch, Vendor Advisory
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.