CVE-2026-55138 Details
Description
Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
A vulnerability exists in Microsoft Office Excel due to an untrusted pointer dereference, which can lead to unauthorized information disclosure. This issue allows an attacker to read small portions of heap memory locally. The vulnerability affects multiple Excel versions, including Excel 2016 (32-bit and 64-bit editions), Excel 2019 (32-bit and 64-bit editions), Office LTSC 2021 (32-bit and 64-bit editions), Office LTSC for Mac 2021, Office LTSC for Mac 2024, and Microsoft 365 Apps for Enterprise (32-bit and 64-bit systems).
Users can download the security update for this vulnerability through the Microsoft Update Catalog or via the Office Update mechanism. For Office 365 for Mac, the update is available through the Microsoft AutoUpdate tool.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 14, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55138 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-822 | Untrusted Pointer Dereference | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| microsoft 365 apps | All versions |
CPE
Remediation
| |
| microsoft excel | 2016 |
CPE
Remediation
| |
| microsoft microsoft 365 | All versions |
CPE
Remediation
| |
| microsoft office 2019 | All versions |
CPE
Remediation
| |
| microsoft office 2021 | All versions |
CPE
Remediation
| |
| microsoft office 2024 | All versions |
CPE
Remediation
| |
| microsoft office online server | < 16.0.10417.20175 |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | Initial Analysis | [email protected] |
| Jul 14, 2026 | CVE Modified | CISA-ADP |
| Jul 14, 2026 | New CVE Received | [email protected] |