Ultimate Posts Widget < 2.3.1 - Admin+ Stored XSS

2024-02-1300:00:00

Dmitrii ignatyev

admin

ultimate posts widget

stored xss

widget editing

xss

frontend exploit

mouseover trigger

7.9 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

8.7%

JSON

Description The plugin does not validate and escape some of its Widget options before outputting them back in attributes, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)

As admin, create/edit an Ultimate Post widget and put the following payload in the Title, URL or "CSS Classes" fields: " onmouseover="alert(/XSS/)"

The XSS will be triggered when a user move their mouse over
- the title of the widget on page where the widget is output
- the related field when editing the widget

Other payload, for the URL field to trigger in the frontend: ' onmouseover=alert(/XSS-URL/)// and javascript:alert(/XSS/)