CVE-2026-55690
Received Received - Intake

Stored XSS in MediaWiki EmbedVideo Extension

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: GitHub, Inc.

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-55690
EUVD
EUVD-2026-78831

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
mediawiki embedvideo 4.1.0

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This is a Stored Cross-Site Scripting (XSS) vulnerability in the MediaWiki EmbedVideo extension. It occurs when an attacker provides an unknown service name to the embedvideo function, causing an error message to render with unsanitized input. This unsanitized input can include malicious HTML or JavaScript, which executes when other users view the page.

Detection Guidance

To detect this vulnerability, check the version of the EmbedVideo extension installed on your MediaWiki instance. If the version is 4.0.0 or lower, the system is vulnerable. You can verify the version by inspecting the extension files or using MediaWiki's Special:Version page.

Impact Analysis

An attacker can inject stored HTML or JavaScript into wiki pages, causing arbitrary code execution for all visitors. This happens without requiring user interaction and affects all editable pages. The impact includes potential data theft, session hijacking, or defacement of wiki content.

Mitigation Strategies

Immediately update the EmbedVideo extension to version 4.1.0 or later. This version includes patches that sanitize error messages and prevent XSS attacks. Follow the official release notes for installation instructions.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-55690. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart