CVE-2026-88154: Microsoft Office Excel Information Disclosure Vulnerability

Overview

Severity

Medium (CVSS 6.5)

CVSS Vector

CVSS:3.1/AV:N/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-Oct

Released

2026-10-13

Description

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

FAQ

Is the Preview Pane an attack vector for this vulnerability? Yes, the Preview Pane is an attack vector. 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.

Affected Products (7)

Microsoft Office

• Microsoft 365 Apps for Enterprise for 32-bit Systems
• Microsoft 365 Apps for Enterprise for 64-bit Systems
• Microsoft Office LTSC 2021 for 64-bit editions
• Microsoft Office LTSC 2021 for 32-bit editions
• Microsoft Office LTSC 2024 for 32-bit editions
• Microsoft Office LTSC 2024 for 64-bit editions
• Microsoft Office 365 for Mac

Acknowledgments

<a href="https://x.com/seadragnol">SeaDragnoL</a> with <a href="https://x.com/qriousec">Qrious Secure</a>, <a href="https://x.com/gr4ss341">grass</a> with <a href="https://x.com/vcslab">Viettel Cyber Security</a>, <a href="https://www.linkedin.com/in/jaemin-kim-b99503278/">jmini</a>, <a href="https://www.linkedin.com/in/jaemin-kim-b99503278/">boolgombear</a>

Revision History

• 2026-10-13: Information published.