What is CVE-2026-70309?

CVE-2026-70309 is a medium-severity vulnerability in Microsoft Edge (Chromium-Based), classified under Origin Validation Error. CVSS score: 5.4/10. Published 2026-08-28.

How severe is CVE-2026-70309?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Vulnerability in Microsoft Edge (Chromium-Based)

CVE-2026-70309

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

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.

Affected products

Microsoft Edge (Chromium-based)

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

secure@microsoft.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-70309?: CVE-2026-70309 is a medium-severity vulnerability in Microsoft Edge (Chromium-Based), classified under Origin Validation Error. CVSS score: 5.4/10. Published 2026-08-28.
How severe is CVE-2026-70309?: Medium severity. CVSS v3 base score is 5.4 out of 10.