Exploited vulnerability · CISA KEV

Is CVE-2021-38646 exploited? Yes: in CISA KEV since 28 Mar 2022

Gociux · Microsoft Office · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2021-38646, Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 28 Mar 2022, 194 days after it was published. It is known to be used in ransomware campaigns. It affects Microsoft Office. If you run it, CISA's required action is: Apply updates per vendor instructions.

What it is

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

What to do

1. Check whether you run it. Look for Office in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
2. Apply the fix. Apply updates per vendor instructions.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 15 Sep 2021.
4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

Other exploited CVEs in Office

• CVE-2026-124194: Microsoft Office Outlook Missing User Interaction for Potentially Unsafe Action Vulnerability (10 Nov 2026)
• CVE-2009-0238: Microsoft Office Remote Code Execution (14 Apr 2026)
• CVE-2026-21514: Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability (10 Feb 2026)
• CVE-2026-21509: Microsoft Office Security Feature Bypass Vulnerability (26 Jan 2026)
• CVE-2009-0556: Microsoft Office PowerPoint Code Injection Vulnerability (7 Jan 2026)
• CVE-2007-0671: Microsoft Office Excel Remote Code Execution Vulnerability (12 Aug 2025)

References

• nvd.nist.gov/vuln/detail/CVE-2021-38646

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in March 2022 · Microsoft scorecard · act-now radar.