Headline
GHSA-4j5h-mvj3-m48v: Star Citizen EmbedVideo Extension Stored XSS through wikitext caused by usage of non-reserved data attributes
Summary
The EmbedVideo extension allows adding arbitrary attributes to an HTML element, allowing for stored XSS through wikitext.
Details
The attributes of an iframe are populated with the value of an unreserved data attribute (data-iframeconfig) that can be set via wikitext:
https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/440fb331a84b2050f4cc084c1d31d58a1d1c202d/resources/ext.embedVideo.videolink.js#L5-L20
Similar code is also present here:
https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/440fb331a84b2050f4cc084c1d31d58a1d1c202d/resources/modules/iframe.js#L139-L155
It is possible to execute JS through attributes like onload or onmouseenter.
PoC
- Create a page with the following contents:
<div class="embedvideo-evl" data-iframeconfig='{"onload": "alert(1)"}'>Click me!</div>
<evlplayer></evlplayer>
- Click on the “Click me!” text
- Click on the “Load video” button below <img width="855" height="404" alt="image" src="https://github.com/user-attachments/assets/afb3839a-012c-4e90-a208-a6137b704ccd" />
Impact
Arbitrary HTML can be inserted into the DOM by any user, allowing for JavaScript to be executed.
Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.