What is CVE-2026-66313?

CVE-2026-66313 is a medium-severity vulnerability in Microsoft Edge Chromium, classified under Origin Validation Error. CVSS score: 6.8/10. Published 2026-08-04.

How severe is CVE-2026-66313?

Medium severity. CVSS v3 base score is 6.8 out of 10.

Vulnerability in Microsoft Edge Chromium

CVE-2026-66313

Origin validation error in Microsoft Edge (Chromium-based) allows an unauthorized attacker to perform tampering locally.

EPSS: 0.002 (6.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/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) Tampering Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-66313?: CVE-2026-66313 is a medium-severity vulnerability in Microsoft Edge Chromium, classified under Origin Validation Error. CVSS score: 6.8/10. Published 2026-08-04.
How severe is CVE-2026-66313?: Medium severity. CVSS v3 base score is 6.8 out of 10.