# CVE-2026-100208: Microsoft Office Outlook integer overflow remote code execution

Source: https://junglewise.ai/threats/cve-2026-100208-integer-overflow-or-wraparound-in-microsoft-office-outlook  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-25. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-100208 · Severity: high · CVSS 7.5 · Published 2026-09-25

Microsoft Office Outlook is an email and calendar application used by millions for business and personal communication. An integer overflow vulnerability allows an attacker to send a specially crafted network message that causes Outlook to execute arbitrary code on the victim's computer, potentially granting full system access.

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

## Quick answers

**Is CVE-2026-100208 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100208 being exploited in the wild.

**How severe is CVE-2026-100208?** High severity, with a CVSS score of 7.5, published 25 September 2026.

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

**Is there a fix for CVE-2026-100208?** 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-2026-100208 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-100208?** Check whether you run Microsoft Office Outlook. 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

An integer overflow or wraparound condition in Microsoft Office Outlook permits remote code execution via network-based attack vectors. The vulnerability requires no authentication or user interaction beyond opening a message, and successful exploitation grants the attacker code execution in the context of the Outlook process. A patch is available from Microsoft.

## Affected products

- Microsoft Office Outlook

## Timeline

- 2026-09-25: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-100208](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-100208)

## Related threats

- [Microsoft Office Outlook path traversal in pathname handling](https://junglewise.ai/threats/cve-2026-124228-improper-limitation-of-a-pathname-to-a-restricted-directory-path)
- [Microsoft Office Outlook use of uninitialized resource code execution](https://junglewise.ai/threats/cve-2026-124227-use-of-uninitialized-resource-in-microsoft-office-outlook-allows)
- [Microsoft Office Outlook user warning spoofing vulnerability](https://junglewise.ai/threats/cve-2026-124194-microsoft-office-outlook-missing-user-interaction-for)
- [Microsoft Office Outlook heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-123383-heap-based-buffer-overflow-in-microsoft-office-outlook-allows-an)
- [Microsoft Office Outlook untrusted pointer dereference](https://junglewise.ai/threats/cve-2026-123382-untrusted-pointer-dereference-in-microsoft-office-outlook-allows)