CVE-2021-42292: Microsoft Excel security feature bypass via crafted file

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 17 September 2026. Confidence: medium.

high priorityThe flaw is confirmed exploited in the wild per CISA KEV and has a high EPSS score, though it requires user interaction to trigger.

What it is

CVE-2021-42292 is a security feature bypass in Microsoft Excel and related Office products. The record gives only a one-line description, so the exact bypassed protection is not stated, but the CVSS vector indicates a local attacker can achieve high confidentiality, integrity and availability impact after a user opens a malicious file. It matters because the flaw is listed in CISA's Known Exploited Vulnerabilities catalog, meaning it has been used in the wild.

Impact

An attacker who gets a victim to open a crafted Excel document can bypass an Excel security feature and gain code execution in the context of the user, with high impact to confidentiality, integrity and availability.

Attack surface

Reached locally by opening a malicious Excel file; the vector requires user interaction (UI:R) and no privileges (PR:N), so the victim must open the document. No remote network vector is indicated.

Exploitation

CVE-2021-42292 is in CISA's KEV catalog (added 2021-11-17), confirming known exploitation, and EPSS shows a 30-day probability of about 0.43 (98.65th percentile). No ransomware campaign use is documented in the record.

What to do

• Apply the Microsoft updates referenced in the MSRC advisory for all affected Excel and Office versions.
• Block or restrict opening of untrusted Excel attachments and downloads at the email and web gateway.
• Enable Protected View and disable macros for documents from untrusted sources.
• Track KEV remediation deadlines and confirm all affected endpoints are patched.
• Limit the use of high-privilege accounts for routine document opening.

Detection

• Monitor for Excel processes spawning child processes such as cmd.exe, powershell.exe or script hosts.
• Alert on Excel opening files from email attachment or download directories followed by unusual network or file activity.
• Hunt for known malicious document hashes and file names associated with this CVE in email and endpoint telemetry.
• Review endpoint logs for Office applications loading unexpected DLLs or writing executables to user-writable paths.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.