What is CVE-2026-77491?

CVE-2026-77491 is a medium-severity vulnerability in Microsoft Windows 10 1607, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-09-08.

How severe is CVE-2026-77491?

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

Out-of-bounds Read in Microsoft Windows 10 1607

CVE-2026-77491

Out-of-bounds read in Windows GDI allows an unauthorized attacker to disclose information locally.

Vulnerability class: Buffer Overflow

Published 2026-09-08 · last modified 2026-09-24.

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: 0.004 (36.8th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.8% 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: 0.004 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

Windows GDI Information Disclosure Vulnerability (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-77491?: CVE-2026-77491 is a medium-severity vulnerability in Microsoft Windows 10 1607, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-09-08.
How severe is CVE-2026-77491?: Medium severity. CVSS v3 base score is 5.5 out of 10.