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      <base href="https://bugs.webkit.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Add flags allow-popups-to-escape-sandbox and allow-modals to iframe sandbox"
   href="https://bugs.webkit.org/show_bug.cgi?id=158875">158875</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Add flags allow-popups-to-escape-sandbox and allow-modals to iframe sandbox
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>WebKit Nightly Build
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Critical
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Layout and Rendering
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>lubin2010&#64;gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>simon.fraser&#64;apple.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>There have been some improvements proposed to iframe sandbox:
<a href="https://wiki.whatwg.org/wiki/Iframe_sandbox_improvments">https://wiki.whatwg.org/wiki/Iframe_sandbox_improvments</a>
<a href="https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-popups-to-escape-sandbox">https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-popups-to-escape-sandbox</a>
<a href="https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-modals">https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-modals</a>

The reasoning behind these improvements is to make iframe sandbox usable for framed unsafe content (e.g., advertisements) and to disallow modal dialogs by default in sandboxed iframe:
allow-popups-to-escape-sandbox: With this flag, if a user interacts with an ad and clicks on it, it should be able to open up the ads landing page as a top level page in a new tab without being sandboxed.
allow-modals: The content inside sandboxed iframe should not be able to open modal dialogs unless this flag is specified.

Both Chrome and Firefox are supporting the new attributes now:
<a href="https://googlechrome.github.io/samples/allow-popups-to-escape-sandbox/index.html">https://googlechrome.github.io/samples/allow-popups-to-escape-sandbox/index.html</a>
<a href="https://googlechrome.github.io/samples/block-modal-dialogs-sandboxed-iframe/">https://googlechrome.github.io/samples/block-modal-dialogs-sandboxed-iframe/</a>
<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1190641">https://bugzilla.mozilla.org/show_bug.cgi?id=1190641</a></pre>
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      </p>
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