This article is a part of our Vulnerability Database (back to index)
Cross-site Scripting occurrences in Nextcloud
A reflected Cross-Site Scripting vulnerability in Nextcloud Server 16.0.1 was discovered in the svg generation. (2020-02-04, CVE-2020-8120)
Missing sanitization in the iOS App 2.24.4 causes an XSS when opening malicious HTML files. (2020-02-04, CVE-2019-15614)
Improper sanitization of HTML in directory names in the Nextcloud Android app prior to version 3.7.0 allowed to style the directory name in the header bar when using basic HTML. (2019-07-30, CVE-2019-5450)
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>