# CVE-2026-78524: Microsoft Office out-of-bounds write in document handling

Source: https://junglewise.ai/threats/cve-2026-78524-microsoft-office-out-of-bounds-write-in-document-handling  
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-2026-78524 · Severity: high · CVSS 8.8 · Published 2026-09-08

Microsoft Office is a widely-used suite of productivity applications for document creation and editing. An out-of-bounds write vulnerability in Office's document processing could allow an attacker to execute arbitrary code on a user's computer when a malicious document is opened, potentially leading to data theft, system compromise, or ransomware installation.

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

## Quick answers

**Is CVE-2026-78524 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78524 being exploited in the wild.

**How severe is CVE-2026-78524?** High severity, with a CVSS score of 8.8, published 8 September 2026.

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

**Is there a fix for CVE-2026-78524?** 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-2026-78524 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-78524?** 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

This is an out-of-bounds write vulnerability in Microsoft Office's document parsing logic. The vulnerability allows remote code execution when a specially crafted Office document is processed. An attacker can deliver the malicious document via email, web download, or file sharing, and if a user opens it, the attacker gains code execution in the context of the Office application. While not yet observed in active exploits in the wild, the high CVSS score (8.8) indicates significant severity and network-accessible attack vector. Microsoft has issued a security update to address this flaw.

## Affected products

- Microsoft Office

## Timeline

- 2026-09-08: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78524](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78524)

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