What is CVE-2026-66318?

CVE-2026-66318 is a high-severity vulnerability in Microsoft Edge Chromium, classified under Origin Validation Error. CVSS score: 8.1/10. Published 2026-08-04.

How severe is CVE-2026-66318?

High severity. CVSS v3 base score is 8.1 out of 10.

Vulnerability in Microsoft Edge Chromium

CVE-2026-66318

Origin validation error in Microsoft Edge (Chromium-based) allows an unauthorized attacker to disclose information over a network.

EPSS: 0.002 (15.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.

Affected products

Microsoft Edge_chromium
Microsoft Edge (Chromium-based) — versions 1.0.0.0

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

Microsoft Edge (Chromium-based) Information Disclosure Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-66318?: CVE-2026-66318 is a high-severity vulnerability in Microsoft Edge Chromium, classified under Origin Validation Error. CVSS score: 8.1/10. Published 2026-08-04.
How severe is CVE-2026-66318?: High severity. CVSS v3 base score is 8.1 out of 10.