Stack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute arbitrary code locally on the affected system. The flaw results from improper bounds checking during processing of a malicious Office document and leads to the attacker’s code running with the privileges of the user who opens the file. The vulnerability is a classic stack buffer overflow (CWE-121) and can compromise confidentiality, integrity, and availability if the attacker succeeds.

Microsoft Office products including Office 2016, Office 2019, Office 2021, Office 2024, Microsoft 365 Apps for Enterprise, Microsoft Office 365 for Mac, Microsoft Office LTSC 2021, Microsoft Office LTSC 2024, Microsoft Office LTSC for Mac 2021, Microsoft Office LTSC for Mac 2024, and Microsoft Word 2016. SharePoint Server editions 2016, 2019, Subscription Edition, and SharePoint Enterprise Server 2016 are also impacted. The broad array of affected Windows and Mac platforms means many corporate desktops and servers could be at risk.

The CVSS score of 7.8 indicates moderate to high severity, while the EPSS score of less than 1% suggests that in the current environment the likelihood of exploitation is low. The vulnerability is not listed in the CISA KEV catalog. Likely exploitation occurs when a malicious Office document is opened, either via email or a shared network location, triggering the buffer overflow. No specific conditions are required beyond the user opening a crafted document, making the attack vector straightforward for an attacker with access to deliver such a file.