CVE-2026-55054: Microsoft 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-Jul
- Released
- 2026-07-14
Description
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
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.
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.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
Affected Products (14)
Microsoft Office
- Office Online Server
- 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 Office LTSC 2024 for 32-bit editions
- Microsoft Office LTSC 2024 for 64-bit editions
- Microsoft Office LTSC for Mac 2024
- Microsoft Excel 2016 (32-bit edition)
- Microsoft Excel 2016 (64-bit edition)
- Microsoft Office 365 for Mac
Security Updates (4)
Acknowledgments
0ccbbf129444eb66344ccafb92b00df4
Revision History
- 2026-07-14: Information published.