CVE-2026-55949 Details
Description
Use of uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
A vulnerability allowing remote code execution has been identified in Microsoft Office Excel. This issue arises from the use of uninitialized resources, which can be exploited by an unauthorized attacker to execute code locally. The vulnerability affects multiple versions of Excel, including Excel 2016 (both 32-bit and 64-bit editions), Excel for Mac 2021 and 2024, Office LTSC 2021 and 2024 (both 32-bit and 64-bit editions), and Office 365 Apps for Enterprise (also in 32-bit and 64-bit versions).
Users can download the security update for this vulnerability through the Microsoft Update Catalog. Specific update links are available for each affected Excel version.
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 15, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55949 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-908 | Use of Uninitialized Resource | [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
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | Initial Analysis | [email protected] |
| Jul 15, 2026 | CVE Modified | CISA-ADP |
| Jul 15, 2026 | CVE Modified | CISA-ADP |
| Jul 14, 2026 | New CVE Received | [email protected] |