Published May 28, 2026Sources checked Nov 11, 2026
4.2MEDIUMCVSS out of 10
What this means
Review the available evidence
CVE-2026-9986 and is rated Medium severity with a CVSS score of 4.2. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: May 29, 2026
Release Notes
Vendor-listed releases
148.0.3967.96
CISA KEVNot listedBased on the latest collected catalog
EPSS0.1%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-9986?
Insufficient validation of untrusted input in OptimizationGuide in Google Chrome prior to 148.0.7778.216 allowed a remote attacker who had compromised the renderer process to perform UI spoofing via a crafted HTML page. (Chromium security severity: High)