Vulnerability in Google Chrome
CVE-2025-9866
Inappropriate implementation in Extensions in Google Chrome prior to 140.0.7339.80 allowed a remote attacker to bypass content security policy via a crafted HTML page. (Chromium security severity: Medium)
EPSS: 0.004 (27.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
Affected products
- Google Chrome — versions 140.0.7339.80
Weakness classification (CWE)
Public proof-of-concept exploits
References
- chrome-cve-admin@google.com (Release Notes)
- chrome-cve-admin@google.com (Permissions Required, Issue Tracking)
Frequently asked questions
- What is CVE-2025-9866?
- CVE-2025-9866 is a high-severity vulnerability in Google Chrome, classified under Protection Mechanism Failure. CVSS score: 8.8/10. Published 2025-09-03.
- How severe is CVE-2025-9866?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2025-9866 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.