CVE-2026-85875: Microsoft Office Excel Information Disclosure Vulnerability

Overview

Severity

Medium (CVSS 5.5)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Category

Information Disclosure

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Sep

Released

2026-09-08

Last Updated

2026-09-17

EPSS Score

0.54% (percentile: 44.7%)

Description

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

FAQ

What type of information could be disclosed by this vulnerability? An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory. According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do? An attacker must send a user a malicious Office file and convince them to open it. Are the updates for Microsoft Office LTSC for Mac 2021 and 2024 currently available? Yes. As of September 16, 2026, the security update for Microsoft Office LTSC for Mac 2021, 2024 and Microsoft Office 365 for Mac are available. Customers running Microsoft Office LTSC for Mac 2021, 2024 and Microsoft Office 365 for Mac should ensure the update is installed to be protected from this vulnerability. Is the Preview Pane an attack vector for this vulnerability? No, the Preview Pane is not an attack vector.

Affected Products (15)

Microsoft Office

• Microsoft Office 2016 (64-bit edition)
• Microsoft Office 2016 (32-bit edition)
• Microsoft 365 Apps for Enterprise for 32-bit Systems
• Microsoft Office LTSC 2024 for 32-bit editions
• Microsoft Office LTSC for Mac 2021
• Microsoft Office 2019 for 64-bit editions
• Microsoft Office LTSC for Mac 2024
• Microsoft Excel 2016 (64-bit edition)
• Microsoft Office 365 for Mac
• Microsoft Office LTSC 2024 for 64-bit editions
• Microsoft Office LTSC 2021 for 32-bit editions
• Microsoft 365 Apps for Enterprise for 64-bit Systems
• Microsoft Excel 2016 (32-bit edition)
• Microsoft Office LTSC 2021 for 64-bit editions
• Microsoft Office 2019 for 32-bit editions

Security Updates (4)

• 5002904
• Release Notes
• 5002914
• Release Notes

Acknowledgments

0ccbbf129444eb66344ccafb92b00df4

Revision History

• 2026-09-08: Information published.
• 2026-09-17: Microsoft is announcing the availability of the security updates for Microsoft Office for Mac. Customers running affected Mac software should install the update for their product to be protected from this vulnerability. Customers running other Microsoft Office software do not need to take any action. See the Release Notes for more information and download links.