CVE-2025-9866

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-03 · updated 2026-09-26
Weakness: CWE-693

Description

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)

Affected products

Google Chrome: before 140.0.7339.80 — fixed in 140.0.7339.80

How to fix

Upgrade to a fixed version: Google Chrome 140.0.7339.80. Check the vendor advisory for mitigations.

References

https://chromereleases.googleblog.com/2025/09/stable-channel-update-for-desktop.html
https://issues.chromium.org/issues/379337758

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