CVE-2026-55899: CWE-121: Stack-based Buffer Overflow in Microsoft Microsoft 365 Apps for Enterprise
Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-55899) is a stack-based buffer overflow in Microsoft Office Excel, part of Microsoft 365 Apps for Enterprise. It enables unauthorized local code execution due to improper handling of input data on the stack. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability. The vulnerability affects version 16.0.1 specifically. Microsoft has released an official fix and manages remediation for this cloud service. No active exploitation has been reported.
Potential Impact
Successful exploitation could allow an attacker to execute arbitrary code locally, potentially leading to full compromise of the affected system's confidentiality, integrity, and availability. The vulnerability is rated high severity with a CVSS score of 7.8. There are no reports of known exploits in the wild.
Mitigation Recommendations
An official fix is available from Microsoft. Since this is a cloud-hosted service, Microsoft manages the remediation server-side. Users should apply the official update as provided in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55899 to mitigate this vulnerability.
CVE-2026-55899: CWE-121: Stack-based Buffer Overflow in Microsoft Microsoft 365 Apps for Enterprise
Description
Stack-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
CVSS v3.1
Score 7.8high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-55899) is a stack-based buffer overflow in Microsoft Office Excel, part of Microsoft 365 Apps for Enterprise. It enables unauthorized local code execution due to improper handling of input data on the stack. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability. The vulnerability affects version 16.0.1 specifically. Microsoft has released an official fix and manages remediation for this cloud service. No active exploitation has been reported.
Potential Impact
Successful exploitation could allow an attacker to execute arbitrary code locally, potentially leading to full compromise of the affected system's confidentiality, integrity, and availability. The vulnerability is rated high severity with a CVSS score of 7.8. There are no reports of known exploits in the wild.
Mitigation Recommendations
An official fix is available from Microsoft. Since this is a cloud-hosted service, Microsoft manages the remediation server-side. Users should apply the official update as provided in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55899 to mitigate this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- microsoft
- Date Reserved
- 2026-06-17T17:36:34.621Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- official-fix
- Is Cloud Service
- true
- Vendor Advisory Urls
- [{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55899","vendor":"Microsoft"}]
Threat ID: 6a566f8168715ace43e6bfa2
Added to database: 07/14/2026, 17:18:57 UTC
Last enriched: 08/13/2026, 15:43:29 UTC
Last updated: 08/27/2026, 22:52:12 UTC
Views: 46
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