Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 28765)
+++ src/wp-includes/formatting.php	(working copy)
@@ -203,7 +203,7 @@
 		. '|'
 		.	'\['		// Find start of shortcode.
 		.	'\[?'		// Shortcodes may begin with [[
-		.	'[^\[\]<>]+'	// Shortcodes do not contain other shortcodes or HTML elements.
+		.	'[^\[\]]+'	// Shortcodes do not contain other shortcodes.  HTML recursion is permitted, but not texturized.
 		.	'\]'		// Find end of shortcode.
 		.	'\]?'		// Shortcodes may end with ]]
 		. ')/s';
@@ -220,12 +220,12 @@
 				_wptexturize_pushpop_element( $curl, $no_texturize_tags_stack, $no_texturize_tags, '<', '>' );
 			}
 
-		} elseif ( '[' === $first && 1 === preg_match( '/^\[[^\[\]<>]+\]$/', $curl ) ) {
+		} elseif ( '[' === $first && 1 === preg_match( '/^\[[^\[\]]+\]$/', $curl ) ) {
 			// This is a shortcode delimeter.
 
 			_wptexturize_pushpop_element( $curl, $no_texturize_shortcodes_stack, $no_texturize_shortcodes, '[', ']' );
 
-		} elseif ( '[' === $first && 1 === preg_match( '/^\[\[?[^\[\]<>]+\]\]?$/', $curl ) ) {
+		} elseif ( '[' === $first && 1 === preg_match( '/^\[\[?[^\[\]]+\]\]?$/', $curl ) ) {
 			// This is an escaped shortcode delimeter.
 
 			// Do not texturize.
Index: tests/phpunit/tests/formatting/WPTexturize.php
===================================================================
--- tests/phpunit/tests/formatting/WPTexturize.php	(revision 28765)
+++ tests/phpunit/tests/formatting/WPTexturize.php	(working copy)
@@ -1186,8 +1186,8 @@
 				'[code]...[/code]]...', // This test would not pass in 3.9 because the extra brace was always ignored by texturize.
 			),
 			array(
+				'[gal>ery ...]', // This is a potentially usable shortcode.
 				'[gal>ery ...]',
-				'[gal>ery &#8230;]',
 			),
 			array(
 				'[gallery ...',
@@ -1194,8 +1194,8 @@
 				'[gallery &#8230;',
 			),
 			array(
+				'[gallery <br ... /> ...]', // This tag is still valid. Shortcode 'attributes' are not considered in the initial parsing of shortcodes, and HTML is allowed.
 				'[gallery <br ... /> ...]',
-				'[gallery <br ... /> &#8230;]',
 			),
 			array(
 				'<br [gallery ...] ... />',
@@ -1234,8 +1234,8 @@
 				'[/gallery ...]]',
 			),
 			array(
+				'[[gallery <br ... /> ...]]', // This gets parsed as an escaped shortcode with embedded HTML.  Brains may explode.
 				'[[gallery <br ... /> ...]]',
-				'[[gallery <br ... /> &#8230;]]',
 			),
 			array(
 				'<br [[gallery ...]] ... />',