The PDF functionality in Google Chrome before 20.0.1132.57 does not properly handle JavaScript code, which allows remote attackers to cause a denial of service (incorrect object access) or possibly have unspecified other impact via a crafted document.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A15039
http://googlechromereleases.blogspot.com/2012/07/stable-channel-update.html