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Cross-site Scripting occurrences in Simply Gallery Blocks With Lightbox
A stored cross-site scripting vulnerability has been discovered in : Simply Gallery Blocks with Lightbox (Version – 2.2.0 & below). The vulnerability exists in the Lightbox functionality where a user with low privileges is allowed to execute arbitrary script code within the context of the application. This vulnerability is due to insufficient validation of image parameters in meta data. (2021-08-30, CVE-2021-24667)
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>