If [age with undefined charset is displayed in frame, codepage of parent page is used. It makes it possible to conduct crossite scripting attack with e.g. UTF-7, EUC-JP (SHIFT_JIS) charset.
CVE-2007-1115 (The child frames in Opera 9 before 9.20 inherit the default charset from the parent window when a charset is not specified in an HTTP Content-Type header or META tag, which allows remote attackers to conduct cross-site scripting (XSS) attacks, as demonstrated using the UTF-7 character set.)
CVE-2007-1114 (The child frames in Microsoft Internet Explorer 7 inherit the default charset from the parent window when a charset is not specified in an HTTP Content-Type header or META tag, which allows remote attackers to conduct cross-site scripting (XSS) attacks, as demonstrated using the UTF-7 character set.)
CVE-2007-0996 (The child frames in Mozilla Firefox before 1.5.0.10 and 2.x before 2.0.0.2, and SeaMonkey before 1.0.8 inherit the default charset from the parent window, which allows remote attackers to conduct cross-site scripting (XSS) attacks, as demonstrated using the UTF-7 character set.)
