Update wp_kses_bad_protocol() to recognize &colon; on uri attributes,

whyisjake · whyisjake · commit b1975463dd99 · 2019-12-12T18:10:23.000Z
`wp_kses_bad_protocol()` makes sure to validate that uri attributes don’t contain invalid/or not allowed protocols. While this works fine in most cases, there’s a risk that by using the colon html5 named entity, one is able to bypass this function. Brings r46895 to the 5.3 branch. Props: xknown, nickdaugherty, peterwilsoncc. git-svn-id: https://develop.svn.wordpress.org/branches/5.3@46899 602fd350-edb4-49c9-b593-d223f7449a82
diff --git a/src/wp-includes/kses.php b/src/wp-includes/kses.php
@@ -1665,7 +1665,7 @@ function wp_kses_html_error( $string ) {
  */
 function wp_kses_bad_protocol_once( $string, $allowed_protocols, $count = 1 ) {
 	$string  = preg_replace( '/(&#0*58(?![;0-9])|&#x0*3a(?![;a-f0-9]))/i', '$1;', $string );
-	$string2 = preg_split( '/:|&#0*58;|&#x0*3a;/i', $string, 2 );
+	$string2 = preg_split( '/:|&#0*58;|&#x0*3a;|&colon;/i', $string, 2 );
 	if ( isset( $string2[1] ) && ! preg_match( '%/\?%', $string2[0] ) ) {
 		$string   = trim( $string2[1] );
 		$protocol = wp_kses_bad_protocol_once2( $string2[0], $allowed_protocols );
diff --git a/tests/phpunit/tests/kses.php b/tests/phpunit/tests/kses.php
@@ -179,6 +179,28 @@ function test_wp_kses_bad_protocol() {
 			}
 		}
 
+		$bad_not_normalized = array(
+			'dummy&colon;alert(1)',
+			'javascript&colon;alert(1)',
+			'javascript&CoLon;alert(1)',
+			'javascript&COLON;alert(1);',
+			'javascript&#58;alert(1);',
+			'javascript&#0058;alert(1);',
+			'javascript&#0000058alert(1);',
+			'jav	ascript&COLON;alert(1);',
+			'javascript&#58;javascript&colon;alert(1);',
+			'javascript&#58;javascript&colon;alert(1);',
+			'javascript&#0000058javascript&colon;alert(1);',
+			'javascript&#58;javascript&#0000058alert(1);',
+			'javascript&#58alert(1)',
+		);
+		foreach ( $bad_not_normalized as $k => $x ) {
+			$result = wp_kses_bad_protocol( $x, wp_allowed_protocols() );
+			if ( ! empty( $result ) && 'alert(1);' !== $result && 'alert(1)' !== $result ) {
+				$this->fail( "wp_kses_bad_protocol failed on $k, $x. Result: $result" );
+			}
+		}
+
 		$safe = array(
 			'dummy:alert(1)',
 			'HTTP://example.org/',
