# CVE-2026-55127: Microsoft Office Word heap overflow code execution

Source: https://junglewise.ai/threats/cve-2026-55127-microsoft-office-word-heap-overflow-code-execution  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-55127 · Severity: high · CVSS 7.8 · Published 2026-07-14

A security vulnerability has been identified in Microsoft Office Word and related SharePoint services that could allow an attacker to take control of a user's computer. To exploit this, an attacker would typically need to trick a user into opening a specially crafted malicious file. If successful, the attacker could gain the same permissions as the local user, potentially leading to data theft, unauthorized software installation, or full system compromise.

Technologies: [Microsoft SharePoint Server](https://junglewise.ai/threats/technologies/sharepoint-server), [Microsoft Word](https://junglewise.ai/threats/technologies/word). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-55127 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55127 being exploited in the wild.

**How severe is CVE-2026-55127?** High severity, with a CVSS score of 7.8, published 14 July 2026.

**Which products and versions are affected?** Microsoft Word Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, Office for Mac, SharePoint Server.

**Is there a fix for CVE-2026-55127?** A patch was published on 2026-07-14: Security updates made available via Microsoft MSRC. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55127 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-55127?** Check whether you run Microsoft SharePoint Server or Microsoft Word at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow (CWE-122) exists in Microsoft Office Word. The vulnerability is triggered when the application fails to properly validate input while processing a specially crafted document. An attacker can exploit this by convincing a user to open a malicious file, leading to arbitrary code execution in the context of the current user. The attack vector is local with a requirement for user interaction (UI:R). Affected products include various versions of Microsoft Office (2019, LTSC 2021/2024), Microsoft 365 Apps, and SharePoint Server. Microsoft has released security updates to address this issue.

## Affected products

- Microsoft Microsoft Office Word Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, Office for Mac, SharePoint Server

## Timeline

- 2026-07-14: advisory: Initial disclosure by Microsoft and NVD publication.
- 2026-07-14: patched: Security updates made available via Microsoft MSRC.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55127](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55127)

## Related threats

- [Microsoft Word use-after-free remote code execution](https://junglewise.ai/threats/cve-2026-112735-use-after-free-in-microsoft-office-word-allows-an-unauthorized)
- [Microsoft Word heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-112724-heap-based-buffer-overflow-in-microsoft-office-word-allows-an)
- [Microsoft Word heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-112716-heap-based-buffer-overflow-in-microsoft-office-word-allows-an)
- [Microsoft Word heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-111306-heap-based-buffer-overflow-in-microsoft-office-word-allows-an)
- [Microsoft Office Word heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-110056-heap-based-buffer-overflow-in-microsoft-office-word-allows-an)