This article is a part of our Vulnerability Database (back to index)
Cross-site Scripting occurrences in Mongo-express
mongo-express is a web-based MongoDB admin interface, written with Node.js and express. 1: As mentioned in this issue: https://github.com/mongo-express/mongo-express/issues/577, when the content of a cell grows larger than supported size, clicking on a row will show full document unescaped, however this needs admin interaction on cell. 2: Data cells identified as media will be rendered as media, without being sanitized. Example of different renders: image, audio, video, etc. As an example of type 1 attack, an unauthorized user who only can send a large amount of data in a field of a document may use a payload with embedded javascript. This could send an export of a collection to the attacker without even an admin knowing. Other types of attacks such as dropping a database\collection are possible. (2021-06-21, CVE-2021-21422)
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>