CVE-2026-123376: Microsoft Office Outlook heap-based buffer overflow

CVE-2026-123376 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Outlook is an email and calendar management application used by millions of businesses and individuals. A heap-based buffer overflow vulnerability allows an attacker to execute arbitrary code remotely without requiring user credentials, potentially leading to unauthorized access, data theft, or malware installation.

Technologies: Microsoft Office Outlook. Vendors: Microsoft.

Quick answers

Is CVE-2026-123376 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-123376 being exploited in the wild.
How severe is CVE-2026-123376?
High severity, with a CVSS score of 8.8, published 10 November 2026.
Which products and versions are affected?
Microsoft Office Outlook.
Is there a fix for CVE-2026-123376?
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-2026-123376 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-123376?
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

A heap-based buffer overflow in Microsoft Outlook permits remote code execution via network-based attack vectors. The vulnerability does not require authentication and allows an attacker to achieve arbitrary code execution in the context of the Outlook process.

Affected products

  • Microsoft Office Outlook

Timeline

  • 2026-11-10: disclosed

References

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