Permissions, Privileges, and Access Controls
Mozilla Firefox 4.x through 6, Thunderbird before 7.0, and SeaMonkey before 2.4 do not prevent manual add-on installation in response to the holding of the Enter key, which allows user-assisted remote attackers to bypass intended access restrictions via a crafted web site that triggers an unspecified internal error.
CWE-264 - Permissions Privileges and Access Controls
CWE 264 (permissions, privileges, and access controls) is not a weakness in and of itself, rather it is a category of weaknesses related to the management of permissions, privileges, and other security features used to perform access control. If not addressed, the weaknesses in this category allow attackers to gain privileges for an unintended sphere of control, access sensitive information, and execute arbitrary commands.