A missing authorization check in the Back‑Forward Cache of Google Chrome prior to version 156.0.8078.47 allows a remote attacker who has already compromised the renderer process to serve a crafted HTML page that causes the renderer to bypass site isolation. The flaw does not grant direct escape to the host operating system; rather, it enables the execution of code inside the browser’s sandbox with the same privileges as the renderer process.

All installations of Google Chrome older than 156.0.8078.47 are vulnerable. The vendor identified is Google for its Chrome browser.

The CVSS score of 8.8 classifies this vulnerability as high severity. The EPSS score is less than 1%, indicating a low but non‑zero probability of exploitation. It is not listed in CISA’s Known Exploited Vulnerabilities catalog. The likely attack vector is a remote web page that the victim visits, which delivers a malicious HTML payload in a context controlled by the attacker. Compromise of the renderer process is required to exploit the flaw, after which the attacker can execute code within the browser sandbox and bypass site isolation.