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Update `wp_kses_bad_protocol()` to recognize `:` on uri attribu…

…tes,

`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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whyisjake committed Dec 12, 2019
1 parent 1f7f3f1 commit b1975463dd995da19bb40d3fa0786498717e3c53
Showing with 23 additions and 1 deletion.
  1. +1 −1 src/wp-includes/kses.php
  2. +22 −0 tests/phpunit/tests/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;|:/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 );
@@ -179,6 +179,28 @@ function test_wp_kses_bad_protocol() {
}
}

$bad_not_normalized = array(
'dummy:alert(1)',
'javascript:alert(1)',
'javascript&CoLon;alert(1)',
'javascript:alert(1);',
'javascript:alert(1);',
'javascript:alert(1);',
'javascript&#0000058alert(1);',
'jav ascript:alert(1);',
'javascript:javascript:alert(1);',
'javascript:javascript:alert(1);',
'javascript&#0000058javascript:alert(1);',
'javascript: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/',

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