Apple Safari 4 Beta build 528.16 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a feeds: URI beginning with a (1) % (percent), (2) { (open curly bracket), (3) } (close curly bracket), (4) ^ (caret), (5) ` (backquote), or (6) | (pipe) character, followed by an & (ampersand) character.