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Update wp_kses_bad_protocol() to recognize : on uri attributes,
`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
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Diff for: src/wp-includes/kses.php

+1-1
Original file line numberDiff line numberDiff line change
@@ -1665,7 +1665,7 @@ function wp_kses_html_error( $string ) {
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*/
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function wp_kses_bad_protocol_once( $string, $allowed_protocols, $count = 1 ) {
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$string = preg_replace( '/(&#0*58(?![;0-9])|&#x0*3a(?![;a-f0-9]))/i', '$1;', $string );
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$string2 = preg_split( '/:|&#0*58;|&#x0*3a;/i', $string, 2 );
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$string2 = preg_split( '/:|&#0*58;|&#x0*3a;|:/i', $string, 2 );
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if ( isset( $string2[1] ) && ! preg_match( '%/\?%', $string2[0] ) ) {
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$string = trim( $string2[1] );
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$protocol = wp_kses_bad_protocol_once2( $string2[0], $allowed_protocols );

Diff for: tests/phpunit/tests/kses.php

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Original file line numberDiff line numberDiff line change
@@ -179,6 +179,28 @@ function test_wp_kses_bad_protocol() {
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}
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}
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$bad_not_normalized = array(
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'dummy:alert(1)',
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'javascript:alert(1)',
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'javascript&CoLon;alert(1)',
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'javascript:alert(1);',
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'javascript:alert(1);',
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'javascript:alert(1);',
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'javascript&#0000058alert(1);',
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'jav ascript:alert(1);',
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'javascript:javascript:alert(1);',
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'javascript:javascript:alert(1);',
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'javascript&#0000058javascript:alert(1);',
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'javascript:javascript&#0000058alert(1);',
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'javascript&#58alert(1)',
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);
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foreach ( $bad_not_normalized as $k => $x ) {
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$result = wp_kses_bad_protocol( $x, wp_allowed_protocols() );
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if ( ! empty( $result ) && 'alert(1);' !== $result && 'alert(1)' !== $result ) {
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$this->fail( "wp_kses_bad_protocol failed on $k, $x. Result: $result" );
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}
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}
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$safe = array(
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'dummy:alert(1)',
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'HTTP://example.org/',

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