The PDF functionality in Google Chrome before 21.0.1180.75 allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors that trigger out-of-bounds write operations.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14823
http://googlechromereleases.blogspot.com/2012/08/stable-channel-update.html