Quick answers
- Is CVE-2026-44820 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-44820 being exploited in the wild.
- How severe is CVE-2026-44820?
- High severity, with a CVSS score of 7.8, published 9 June 2026.
- Which products and versions are affected?
- Microsoft Excel.
- Is there a fix for CVE-2026-44820?
- 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-2026-44820 attacked?
- It is attacked with local access, in a network appliance.
- Am I affected by CVE-2026-44820?
- Check whether you run Microsoft Excel. 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 underflow (wraparound) vulnerability exists in Microsoft Office Excel, which can lead to an out-of-bounds memory access (CWE-125). The vulnerability is triggered when the application processes a malformed Excel file. An attacker can exploit this by convincing a user to open a malicious document, leading to arbitrary code execution in the context of the current user. The attack vector is local with a requirement for user interaction (UI:R), and it carries a high impact on confidentiality, integrity, and availability. Microsoft has released security updates to address this issue.
Affected products
- Microsoft Excel
Timeline
- 2026-06-09: disclosed
- 2026-06-09: advisory: Published by Microsoft and NVD