Google » Toolbar » 1.1.57 : Security Vulnerabilities, CVEs,

Cross-site scripting (XSS) vulnerability in Google Toolbar 2.0.114.1 allows remote attackers to inject arbitrary web script via about.html in the About section. NOTE: some followup posts suggest that the demonstration code's use of the res:// protocol does not cross privilege boundaries, since it is not allowed in the Internet Zone. Thus this might not be a vulnerability.

The Google toolbar 1.1.58 and earlier allows remote web sites to monitor a user's input into the toolbar via an "onkeydown" event handler.

The Google toolbar 1.1.58 and earlier allows remote web sites to perform unauthorized toolbar operations including script execution and file reading in other zones such as "My Computer" by opening a window to tools.google.com or the res: protocol, then using script to modify the window's location to the toolbar's configuration URL, which bypasses the origin verification check.