[whatwg] <base> in <body>

Anne van Kesteren annevk at opera.com
Wed Jul 20 01:54:55 PDT 2011

On Wed, 20 Jul 2011 05:07:05 +0200, Boris Zbarsky <bzbarsky at mit.edu> wrote:
> That said, I'm not sure I understand the security concern.  What kind of  
> whitelist-based filter would let through <script>s whose URIs it does  
> not control, exactly?  Can the security concern be mitigated by only  
> allowing <base> outside <head> if the base URI it sets is same-origin  
> with the document?

The <script> is from the page itself and uses a relative URL. The <base>  
is inserted by the attacker and causes the script to be requested from a  
server under the attacker's control.

Anne van Kesteren

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