CVE-2026-55690 EmbedVideo Extension: Stored XSS via unsanitized service name in exception text
A user with edit permissions can inject stored JavaScript via unsanitized service names in error messages, leading to code execution for other visitors.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55690?
CVE-2026-55690 is a high-severity cross-site scripting vulnerability in StarCitizenWiki mediawiki-extensions-EmbedVideo, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The EmbedVideo Extension is a MediaWiki extension which adds a parser function called #ev and various parser tags for embedding video clips from various video sharing services. Prior to 4.1.0, EmbedServiceFactory::newFromName in includes/EmbedService/EmbedServiceFactory.php interpolates an attacker-controlled unknown service name into exception text, and includes/EmbedVideo.php returns that text as HTML through the isHtml output path without neutralization. Both the #ev parser function and the evl parser form can reach this error path. A user able to edit a wiki page can inject stored HTML or JavaScript into the error output, causing code to execute in the wiki origin for visitors who render the page. This issue is fixed in version 4.1.0.
Weakness: CWE-79
Which versions are affected by CVE-2026-55690?
2 open source packages ship an affected version, including starcitizenwiki/embedvideo.
| Package | Affected | Fixed in |
|---|---|---|
starcitizenwiki/embedvideo Packagist | All versions | 4.1.0 |
starcitizenwiki/embedvideo Packagist | All versions | 4.1.0 |
How do I fix CVE-2026-55690?
Upgrade starcitizenwiki/embedvideo to 4.1.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-55690 being exploited?
There is no known exploitation of CVE-2026-55690 in the wild and no public exploit code.
Sources
Also known as GHSA-c29q-5xm7-5p62.