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CVE-2025-9866VulnerabilityPublished

Extensions · Inappropriate Implementation

Affects chromeSource GCVE Database

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Authoritative record:CVE-2025-9866· High 8.8

Not known to be exploited · CVSS 8.8 High : upgrade to 140.0.7339.80 soon.

Data as of 10 Nov 2026, 23:24 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 140.0.7339.80
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Sep 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade google/chrome to 140.0.7339.80.

Affected software

ProductAffectedFixed in
Googlegoogle/chromepkg:deb/google/chromeOther threatsAffected
  • <140.0.7339.80
Fixed in
  • 140.0.7339.80

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in Google Chrome version 140.0.7339.80. Users and administrators should update to this version or later to remediate the vulnerability. No additional mitigation steps are indicated in the provided data.

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)

References

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