CVE 2005-2266
Firefox before 1.0.5 and Mozilla before 1.7.9 allows a child frame to call top.focus and other methods in a parent frame, even when the parent is in a different domain, which violates the same origin policy and allows remote attackers to steal sensitive information such as cookies and passwords from web sites whose child frames do not verify that they are in the same domain as their parents.
See the 
CVE page on Mitre.org
for more details.
