CVE-2026-120003: Microsoft Office heap-based buffer overflow

CVE-2026-120003 · Severity: high · CVSS 8.8 · Published 2026-11-10

A heap-based buffer overflow vulnerability in Microsoft Office allows attackers to execute malicious code remotely without authentication. This could lead to complete compromise of systems running vulnerable Office versions, enabling data theft, ransomware installation, or lateral movement within a network.

Technologies: Microsoft Office. Vendors: Microsoft.

Quick answers

Is CVE-2026-120003 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-120003 being exploited in the wild.
How severe is CVE-2026-120003?
High severity, with a CVSS score of 8.8, published 10 November 2026.
Which products and versions are affected?
Microsoft Office.
Is there a fix for CVE-2026-120003?
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-2026-120003 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-120003?
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

A heap-based buffer overflow in Microsoft Office enables network-based code execution without requiring prior authentication. The vulnerability is triggered through maliciously crafted Office documents or network packets, allowing an attacker to execute arbitrary code with the privileges of the Office process.

Affected products

  • Microsoft Office

Timeline

  • 2026-11-10: disclosed

References

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