CVE-2026-55690

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.

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.

Summary

When passing an unknown service name to embedvideo, an error message is rendered containing the invalid service name. The service name is not sanitized and can contain HTML.

Details

There is a hardcoded list of allowed services in a switch statement inside EmbedServiceFactory#newFromName here. When the service name is not known, an exception is thrown with the service name injected into the message via sprintf here. This message is not sanitized and is marked as isHtml here. Similarly with {{evl: here.

PoC

// Must be on a page, not on ExpandTemplates
{{#ev:<img src=x onerror=alert(document.domain)>|dQw4w9WgXcQ}}
{{#evl:id=dummy|service=<img src=x onerror=alert(document.domain)>}}

Impact

Stored XSS that allows arbitrary Javascript/HTML insertion on any page that a user can edit. It requires no interaction and executes in the wiki origin for every visitor to the page.

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.

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.

Summary

When passing an unknown service name to embedvideo, an error message is rendered containing the invalid service name. The service name is not sanitized and can contain HTML.

Details

There is a hardcoded list of allowed services in a switch statement inside EmbedServiceFactory#newFromName here. When the service name is not known, an exception is thrown with the service name injected into the message via sprintf here. This message is not sanitized and is marked as isHtml here. Similarly with {{evl: here.

PoC

// Must be on a page, not on ExpandTemplates
{{#ev:<img src=x onerror=alert(document.domain)>|dQw4w9WgXcQ}}
{{#evl:id=dummy|service=<img src=x onerror=alert(document.domain)>}}

Impact

Stored XSS that allows arbitrary Javascript/HTML insertion on any page that a user can edit. It requires no interaction and executes in the wiki origin for every visitor to the page.