[wp-trac] [WordPress Trac] #60243: KSES: Allow encoded images

[WordPress Trac]

#60243: KSES: Allow encoded images
--------------------------+-----------------------------
 Reporter:  Chouby        |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Formatting    |    Version:
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 According to [https://www.rfc-editor.org/rfc/rfc2397 RFC 2397], it is
 possible to include directly some small media instead of using an external
 source.
 For example:
 {{{
 <img
 src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAALCAMAAABBPP0LAAAAh1BMVEXpTFTwNj7rHiTz8/Pv7u7XAgLuKTP4o6f0l5n9/f327e36+vv39/fnaGvtbnPIAAD1jpPwgIPoe4H19fXhPUDwdXfy0NHtY2XoXmLowcLsvr/fREu+AADwiIzy8vLeLzT1mp/qWFjcJSrgUVeyAADs4+PYGx7kBgjprazr6+umAADPz8/ExMQoJmQzAAAAiElEQVR4ASWJRULDUBCGv5l4gm9wVtj9jwNt37LuEveM/Cq0K/TTs7hDMBT9u4EkqNunq2u1AZtrpJ35/Wtpq9M6jev4XGevUQqiH/uyfLDj4JjGH6UtyoyA9Wpmbp+wAf3ybZEg/v1V84WVoFyngbd7KcvWGxtXwVoBxvDPyzlFHAjfAAEqoAEThSiV/9sl/gAAAABJRU5ErkJggg=="
 alt="" width="16" height="11" style="width: 16px;height: 11px">
 }}}

 When passing this small piece of html through `wp_kses_post()`, the
 `data:` part is stripped out like this:

 {{{
 <img
 src="image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAALCAMAAABBPP0LAAAAh1BMVEXpTFTwNj7rHiTz8/Pv7u7XAgLuKTP4o6f0l5n9/f327e36+vv39/fnaGvtbnPIAAD1jpPwgIPoe4H19fXhPUDwdXfy0NHtY2XoXmLowcLsvr/fREu+AADwiIzy8vLeLzT1mp/qWFjcJSrgUVeyAADs4+PYGx7kBgjprazr6+umAADPz8/ExMQoJmQzAAAAiElEQVR4ASWJRULDUBCGv5l4gm9wVtj9jwNt37LuEveM/Cq0K/TTs7hDMBT9u4EkqNunq2u1AZtrpJ35/Wtpq9M6jev4XGevUQqiH/uyfLDj4JjGH6UtyoyA9Wpmbp+wAf3ybZEg/v1V84WVoFyngbd7KcvWGxtXwVoBxvDPyzlFHAjfAAEqoAEThSiV/9sl/gAAAABJRU5ErkJggg=="
 alt="" width="16" height="11" style="width: 16px;height: 11px">
 }}}
 This is resulting in a 404 error for the image source.

 NB: #25851 also refers to encoded images but the reported issue is more
 about large contents and not this specific issue.

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Ticket URL: <https://core.trac.wordpress.org/ticket/60243>
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