What is CVE-2025-12909?

CVE-2025-12909 is a medium-severity vulnerability in Google Chrome, classified under Protection Mechanism Failure. CVSS score: 5.3/10. Published 2025-11-08.

How severe is CVE-2025-12909?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Google Chrome

CVE-2025-12909

Insufficient policy enforcement in Devtools in Google Chrome prior to 140.0.7339.80 allowed a remote attacker to leak cross-origin data via Devtools. (Chromium security severity: Low)

Published 2025-11-08 · last modified 2026-09-30.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.002 (8.3th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 8.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Google Chrome — versions 140.0.7339.80

Weakness classification (CWE)

CWE-693 — Protection Mechanism Failure

References

chromereleases.googleblog.com/2025/09/stable-channel-update-for-desktop.html (Vendor Advisory)
issues.chromium.org/issues/361116749 (Exploit, Issue Tracking)

Frequently asked questions

What is CVE-2025-12909?: CVE-2025-12909 is a medium-severity vulnerability in Google Chrome, classified under Protection Mechanism Failure. CVSS score: 5.3/10. Published 2025-11-08.
How severe is CVE-2025-12909?: Medium severity. CVSS v3 base score is 5.3 out of 10.