[Bug reporting] XSS vulnerabilty in wp_kses_bad_protocol in wp-includes/kses.php (CVE-2019-20041)

[seongil-wi]

Hi

I found a known XSS vulnerability in the recent version of jquery-wp-content.
In particular, the bug we report is a known bug by CVE-2019-20041.

wp_kses_bad_protocol in wp-includes/kses.php in WordPress before 5.3.1 mishandles the HTML5 colon named entity, allowing attackers to bypass input sanitization, as demonstrated by the javascript: substring.

Please check this line:

jquery-wp-content/plugins/vaultpress/class.vaultpress-hotfixes.php

Line 788 in bb05d9c

$string2 = preg_split( '/:|&#0*58;|&#x0*3a;/i', $string, 2 );

Thanks!

[mgol]

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