CVE-2026-81953

This vulnerability is a flaw in how Excel handles certain spreadsheet content. If a user opens a specially made Excel file, it could let an attacker run malicious code on that user’s computer—like turning a harmless document into a delivery vehicle for malware.

This matters if your business uses Microsoft Excel or Microsoft Office on Windows or Mac, including Microsoft 365 Apps and the supported Office 2016/2019/2021/2024 and Mac Office LTSC/Office 365 for Mac products listed.

It’s primarily a risk when an attacker can trick someone into opening a crafted spreadsheet file (user interaction is required). There’s no indication from the findings that exploitation happens without a user opening a malicious document.

Verdict: RED. Even though there’s no KEV listing and no public exploit code on record, this is a serious remote code execution risk tied to opening a malicious Excel file, and Microsoft has already provided fixes.

Act now to reduce the chance that a staff member opening a booby-trapped spreadsheet could lead to malware execution.