CVE-2026-12454: Race in Safe Browsing in Google Chrome on Mac prior to 149

Synopsis

A race condition in the Safe Browsing component of Google Chrome on macOS allows a remote attacker who has already compromised the renderer process to escape the browser sandbox via a crafted HTML page. The vulnerability is reachable over the network, requires no authentication, but does require the victim to visit a malicious page, and the exploit depends on winning a race condition in timing-sensitive code. Successful exploitation gives the attacker full read, write, and crash capability beyond the browser sandbox, effectively taking control of the host process. A patched-image rebuild at version 149.0.7827.155 is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker delivers the crafted HTML page over the network, so the vulnerable service must be reachable from the attacker's origin.

• AuthenticationNot required

  No account or credentials are needed; any unauthenticated user visiting the malicious page is a valid target.

• Victim interactionRequired

  The victim must navigate to or be redirected to the attacker-controlled HTML page, making this a social-engineering or drive-by delivery scenario.

• Attack complexityDetail

  Exploitation depends on winning a race condition in the Safe Browsing component, meaning success is probabilistic and may require repeated attempts or careful timing to achieve sandbox escape.

Blast Radius

• A successful sandbox escape lets the attacker read files and data accessible to the browser process outside the sandbox, including session tokens, cookies, and local user files.
• The attacker gains the ability to write or modify data on the host filesystem at the permission level of the browser process.
• The attacker can crash or destabilize the host browser process and any dependent services running under the same user account.
• Because this is a full sandbox escape, the attacker effectively operates as an unprivileged local user on the macOS host, opening the door to further local privilege escalation.