# CVE-2026-78510: Microsoft Office heap-based buffer overflow allows code execution

Source: https://junglewise.ai/threats/cve-2026-78510-microsoft-office-heap-based-buffer-overflow-allows-code-execution  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-08. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-78510 · Severity: high · CVSS 8.4 · Published 2026-09-08

Microsoft Office contains a heap-based buffer overflow vulnerability that allows an attacker to execute arbitrary code on a user's computer. Exploitation typically requires local access or a user to open a specially crafted file, but successful exploitation could lead to complete system compromise, including theft of sensitive documents and financial data.

Technologies: [Microsoft Office](https://junglewise.ai/threats/technologies/office). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-78510 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78510 being exploited in the wild.

**How severe is CVE-2026-78510?** High severity, with a CVSS score of 8.4, published 8 September 2026.

**Which products and versions are affected?** Microsoft Office.

**Is there a fix for CVE-2026-78510?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-78510 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-78510?** Check whether you run Microsoft Office. 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 exists in Microsoft Office, triggered during memory allocation and write operations when processing certain input. The vulnerability is reachable via file parsing logic—typically when a user opens a malicious Office document. An attacker with local system access or the ability to deliver a crafted file to a target user can overflow the heap buffer, overwriting adjacent memory structures and achieving arbitrary code execution in the context of the Office application. No authentication is required once the file is opened. Patches are expected from Microsoft's regular security update cycle.

## Affected products

- Microsoft Office

## Timeline

- 2026-09-08: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78510](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78510)

## Related threats

- [Microsoft Office Outlook user warning spoofing vulnerability](https://junglewise.ai/threats/cve-2026-124194-microsoft-office-outlook-missing-user-interaction-for)
- [Microsoft Office heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-122198-heap-based-buffer-overflow-in-microsoft-office-allows-an)
- [Microsoft Office heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-120003-heap-based-buffer-overflow-in-microsoft-office-allows-an)
- [Microsoft Office UI security feature bypass](https://junglewise.ai/threats/cve-2026-119998-product-ui-does-not-warn-user-of-unsafe-actions-in-microsoft)
- [Microsoft Office heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-116717-heap-based-buffer-overflow-in-microsoft-office-allows-an)