An attacker who has already compromised the renderer process of Chrome can exploit an insufficient validation of untrusted input in WebAuthn. The flaw allows the attacker to execute code outside the renderer sandbox, effectively achieving a sandbox escape. The weakness stems from inadequate input validation (CWE-20).

Google Chrome desktop versions older than 151.0.7922.72 are affected. The issue is limited to the renderer component and requires a crafted PDF file to trigger.

The vulnerability is scored CVSS 9.6, indicating a high severity. However, the EPSS score is less than 1%, suggesting a very low likelihood of mass exploitation. It is not listed in the CISA KEV catalog. Exploitation requires an attacker to first compromise the renderer process, which can be achieved by delivering a malicious PDF that triggers the WebAuthn flaw. Once the renderer is compromised, the attacker can escape the sandbox and potentially gain execution privileges on the host.