# CVE-2026-65663: Microsoft Office SharePoint deserialization of untrusted data

Source: https://junglewise.ai/threats/cve-2026-65663-microsoft-office-sharepoint-deserialization-of-untrusted-data  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-11. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-65663 · Severity: high · CVSS 8.8 · Published 2026-08-11

Microsoft Office SharePoint contains a flaw in how it processes serialized data from network requests. An authorized user can send specially crafted data to the server that causes it to execute arbitrary code, potentially compromising the integrity and confidentiality of SharePoint servers and the data they store.

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

## Quick answers

**Is CVE-2026-65663 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-65663 being exploited in the wild.

**How severe is CVE-2026-65663?** High severity, with a CVSS score of 8.8, published 11 August 2026.

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

**Is there a fix for CVE-2026-65663?** 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-2026-65663 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-65663?** Check whether you run Microsoft Office SharePoint 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

This vulnerability exists in Microsoft Office SharePoint's deserialization handling, which fails to properly validate untrusted data before reconstruction into objects. The flaw allows an authenticated attacker to send malicious serialized payloads over the network that trigger remote code execution on the server. An attacker must have valid authentication credentials to exploit this vulnerability. Patches are expected from Microsoft's security team for affected versions.

## Affected products

- Microsoft Office SharePoint <UNKNOWN>

## Timeline

- 2026-08-11: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65663](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65663)

## 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)