What is CVE-2026-80084?

CVE-2026-80084 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-09-08.

How severe is CVE-2026-80084?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Out-of-bounds Read in Microsoft 365 Apps

CVE-2026-80084

Out-of-bounds read in Microsoft Office Outlook allows an unauthorized attacker to disclose information over a network.

Vulnerability class: Buffer Overflow

Published 2026-09-08 · last modified 2026-09-10.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.009 (60.0th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 60.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

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

Frequently asked questions

What is CVE-2026-80084?: CVE-2026-80084 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-09-08.
How severe is CVE-2026-80084?: Medium severity. CVSS v3 base score is 6.5 out of 10.