# CVE-2026-109464: Microsoft Office SharePoint deserialization of untrusted data

Source: https://junglewise.ai/threats/cve-2026-109464-deserialization-of-untrusted-data-in-microsoft-office-sharepoint  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-109464 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Office SharePoint, a collaborative platform used by organizations to manage documents and team projects, contains a flaw that allows authenticated attackers to execute arbitrary code through deserialization of malicious data. An attacker with valid SharePoint access could exploit this to gain full control over the system and access sensitive organizational information.

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

## Quick answers

**Is CVE-2026-109464 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109464 being exploited in the wild.

**How severe is CVE-2026-109464?** High severity, with a CVSS score of 8.8, published 10 November 2026.

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

**Is there a fix for CVE-2026-109464?** 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-2026-109464 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-109464?** Check whether you run Microsoft Office SharePoint. 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

The vulnerability exists in SharePoint's deserialization logic, which fails to properly validate untrusted data before processing it. An authenticated attacker can send a specially crafted serialized object over the network to trigger arbitrary code execution. The flaw requires valid SharePoint credentials but no additional user interaction.

## Affected products

- Microsoft Office SharePoint

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-109464](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-109464)

## Related threats

- [Microsoft Office SharePoint privilege escalation via missing authorization](https://junglewise.ai/threats/cve-2026-88176-missing-authorization-in-microsoft-office-sharepoint-allows-an)
- [Microsoft Office SharePoint XSS privilege escalation](https://junglewise.ai/threats/cve-2026-80095-improper-neutralization-of-input-during-web-page-generation-cross)
- [Microsoft Office SharePoint server-side request forgery](https://junglewise.ai/threats/cve-2026-124210-server-side-request-forgery-ssrf-in-microsoft-office-sharepoint)
- [Microsoft Office SharePoint privilege escalation via incorrect authorization](https://junglewise.ai/threats/cve-2026-123391-incorrect-authorization-in-microsoft-office-sharepoint-allows-an)
- [Microsoft Office SharePoint deserialization of untrusted data](https://junglewise.ai/threats/cve-2026-123390-deserialization-of-untrusted-data-in-microsoft-office-sharepoint)