CVE-2026-55056 Details
Description
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
A heap-based buffer overflow vulnerability has been identified in Microsoft Office. This vulnerability allows an unauthorized attacker to execute code locally. It affects several different versions and editions of Microsoft Office, including Office 365 for Mac, Office 2016 (both 32-bit and 64-bit editions), Office LTSC for Mac 2024, Office LTSC 2024 (both 32-bit and 64-bit editions), Office LTSC 2021 (both 32-bit and 64-bit editions), Office LTSC for Mac 2021, Microsoft 365 Apps for Enterprise (both 32-bit and 64-bit systems), and Office 2019 (both 32-bit and 64-bit editions).
Users can download the security update for this vulnerability through the Microsoft Update Catalog. Specific download links are available in the Microsoft Knowledge Base articles for each affected Office 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-2026-55056 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-787 | Out-of-bounds Write | [email protected] |
| CWE-122 | Heap-based Buffer Overflow | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| microsoft 365 apps | All versions |
CPE
Remediation
| |
| microsoft microsoft 365 | All versions |
CPE
Remediation
| |
| microsoft office 2016 | 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
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 16, 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] |