Custom Content Shortcode < 4.0.2 - Authenticated Stored Cross-Site Scripting

2022-02-0200:00:00

Francesco Carlucci

106

custom content shortcode

authenticated

stored

cross-site scripting

contributor

custom field

post editor

xss exploit

EPSS

0.001

Percentile

24.8%

JSON

The plugin does not escape custom fields before outputting them, which could allow Contributor+ (v < 4.0.1) or Admin+ (v < 4.0.2) users to perform Cross-Site Scripting attacks even when the unfiltered_html is disallowed. Please note that such attack is still possible by admin+ in single site blogs by default (but won’t be when the unfiltered_html is disallowed)

As a contributor, add a custom field in a post (while in a post editor, open the Options panel > Preferences > Panels and enable the Custom Fields), such as test_xss with a value of <script>alert(/XSS/)</script>

Then add the following shortcode to the post [field test_xss] and view/preview it to trigger the XSS

EPSS

0.001

Percentile

24.8%

JSON

Related for WPEX-ID:E247D78A-7243-486C-A017-7471A8DCB800