When doing Add Media - Insert from URL caption textarea fills with HTML markup due to improper HTML

[mwheelermindbox]

When creating/editing a post and choosing "Add Media" and then "Insert from URL" in the sidebar of the modal, and entering the URL of the image the caption field is filled with the markup for the alignment and link button bars.

Line 1023 of wp-includes/media-template.php is:

<textarea id="embed-image-settings-caption" data-setting="caption" />

but textarea is not allowed to be a self-closing tag, so in Chrome (and possibly other browsers) this textarea gets filled with the markup to control image layout.

This is all fixed if line 1023 is changed to the proper markup of:

<textarea id="embed-image-settings-caption" data-setting="caption"></textarea>

[sabernhardt]

Duplicate of #52065.

@mwheelermindbox Thanks for the report!

The textarea is fixed now, as of changeset:49804. That will be included soon in the next minor version, 5.6.1.