[whatwg] <base> in <body>

Wed Jul 20 07:54:25 PDT 2011

On 7/20/11 4:54 AM, Anne van Kesteren wrote:
> 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.

OK, thanks.  That was about the only threat model I could think of here...

It sounds like my proposal above would mitigate this threat, yes?

-Boris