Published Aug 25, 2026Sources checked Oct 28, 2026
3.1LOWCVSS out of 10
What this means
Review the available evidence
CVE-2026-78953 and is rated Low severity with a CVSS score of 3.1. 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: Aug 28, 2026
Release Notes
Vendor-listed releases
152.0.4191.53
CISA KEVNot listedBased on the latest collected catalog
EPSS0.2%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-78953?
Missing authorization in SiteIsolation in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted PDF file. (Chromium security severity: Medium)