CVE-2026-57440 Mediawiki EmbedVideo Extension has stored XSS via malformed src url with $wgEmbedVideoRequireConsent disabled
Attackers can inject malicious scripts via malformed video URLs in MediaWiki when consent requirements are disabled, potentially compromising user sessions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-57440?
CVE-2026-57440 is a high-severity cross-site scripting vulnerability in StarCitizenWiki mediawiki-extensions-EmbedVideo, published on 24 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, with $wgEmbedVideoRequireConsent disabled (not the default), the urls for videos are passed into an iframe src attribute without sanitization. When given a malformed url or id, the src attribute can be escaped via double quotes, allowing for html/javascript injection. Version 4.1.0 contains a patch.
Which versions are affected by CVE-2026-57440?
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-2026-57440?
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-2026-57440 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-57440 exists.
Sources
Also known as GHSA-v65j-hff3-753c.