Buffer overflow in Microsoft 365 Apps
CVE-2026-66807
Stack-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (37.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
Affected products
- Microsoft 365 Apps
- Microsoft 365
- Microsoft 365 Apps For Enterprise — versions 16.0.1
- Microsoft Office 2019 — versions 19.0.0
- Microsoft Office 365 For Mac — versions 1.0.0
- 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 2019
Weakness classification (CWE)
References
- Microsoft Office Graphics Component Remote Code Execution Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-66807?
- CVE-2026-66807 is a high-severity vulnerability in Microsoft 365 Apps, classified under Stack-based Buffer Overflow. CVSS score: 7.8/10. Published 2026-08-11.
- How severe is CVE-2026-66807?
- High severity. CVSS v3 base score is 7.8 out of 10.