This article is a part of our Vulnerability Database (back to index)
Cross-site Scripting occurrences in Advanced Custom Fields
The Advanced Custom Fields Pro WordPress plugin before 5.9.1 did not properly escape the generated update URL when outputting it in an attribute, leading to a reflected Cross-Site Scripting issue in the update settings page. (2021-04-22, CVE-2021-24241)
The Advanced Custom Fields plugin before 5.8.12 for WordPress mishandles the escaping of strings in Select2 dropdowns, potentially leading to XSS. (2021-01-06, CVE-2020-36172)
The advanced-custom-fields (aka Elliot Condon Advanced Custom Fields) plugin before 5.7.8 for WordPress has XSS by authors. (2019-08-22, CVE-2018-20986)
Why Cross-site Scripting can be dangerous
Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.
The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:
https://server.com/confirmation?message=Transaction+Complete
what results in:
<span>Confirmation: Transaction Complete</span>
In that case the message can be modified to become a valid Javascript code, e.g.:
https://server.com/confirmation?message=<script>dangerous javascript code here</script>
and it will be executed locally by the user's browser with full access to the user's personal application/browser data:
<span>Confirmation: <script>dangerous javascript code here</script></span>