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Cross-site Scripting occurrences in Plantuml
A vulnerability was found in PlantUML 6.43. It has been declared as problematic. Affected by this vulnerability is the component Database Information Macro. The manipulation leads to cross site scripting. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. (2022-06-07, CVE-2020-36523)
XSS via Embedded SVG in SVG Diagram Format in GitHub repository plantuml/plantuml prior to 1.2022.4. Stored XSS in the context of the diagram embedder. Depending on the actual context, this ranges from stealing secrets to account hijacking or even to code execution for example in desktop applications. Web based applications are the ones most affected. Since the SVG format allows clickable links in diagrams, it is commonly used in plugins for web based projects (like the Confluence plugin, etc. see https://plantuml.com/de/running). (2022-04-15, CVE-2022-1231)
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>