CVE-2026-55023: Microsoft Office 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
Unlikely
Patch Tuesday
2026-Jul
Released
2026-07-14

Description

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

FAQ

What type of information could be disclosed by this vulnerability? The type of information that could be disclosed if an attacker successfully exploited this vulnerability is the local memory address. Is the Preview Pane an attack vector for this vulnerability? No, the Preview Pane is not an attack vector. There are multiple update packages available for some of the affected software. Do I need to install all the updates listed in the Security Updates table for the software? Yes. Customers should apply all updates offered for the software installed on their systems. If multiple updates apply, they can be installed in any order. 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.

Affected Products (16)

Microsoft Office

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

Security Updates (8)

Acknowledgments

Haein Lee, HangAn

Revision History

  • 2026-07-14: Information published.