What is CVE-2026-83951?

CVE-2026-83951 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Buffer Over-read. CVSS score: 5.5/10. Published 2026-09-08.

How severe is CVE-2026-83951?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Vulnerability in Microsoft 365 Apps

CVE-2026-83951

Buffer over-read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.

Published 2026-09-08 · last modified 2026-09-08.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (44.7th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 44.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-126 — Buffer Over-read

References

Microsoft Office Word Information Disclosure Vulnerability (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-83951?: CVE-2026-83951 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Buffer Over-read. CVSS score: 5.5/10. Published 2026-09-08.
How severe is CVE-2026-83951?: Medium severity. CVSS v3 base score is 5.5 out of 10.