Out-of-bounds Read in Microsoft 365 Apps For Enterprise
CVE-2026-26109
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
Vulnerability class: Buffer Overflow
EPSS: 0.000 (8.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.4 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C.
Affected products
- Microsoft 365 Apps For Enterprise — versions 16.0.1
- Microsoft Excel 2016 — versions 16.0.0.0
- Microsoft Office 2019 — versions 19.0.0
- Microsoft Office Ltsc 2021 — versions 16.0.1
- Microsoft Office Ltsc 2024 — versions 16.0.0
- Microsoft Office Ltsc For Mac 2021 — versions 16.0.1
- Microsoft Office Ltsc For Mac 2024 — versions 16.0.0
- Microsoft Office Online Server — versions 16.0.0.0
Weakness classification (CWE)
References
- Microsoft Excel Remote Code Execution Vulnerability (vendor-advisory, patch)
Frequently asked questions
- What is CVE-2026-26109?
- CVE-2026-26109 is a high-severity vulnerability in Microsoft 365 Apps For Enterprise, classified under Out-of-bounds Read. CVSS score: 8.4/10. Published 2026-03-10.
- How severe is CVE-2026-26109?
- High severity. CVSS v3 base score is 8.4 out of 10.