The default configuration of the <Button2> binding in Uzbl before 2010.08.05 does not properly use the @SELECTED_URI feature, which allows user-assisted remote attackers to execute arbitrary commands via a crafted HREF attribute of an A element in an HTML document.
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.