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MajorCritical vulnerability

CVE-2026-57440: Mediawiki EmbedVideo Extension has stored XSS via malformed src url with $wgEmbedVideoRequireConsent disabled

GitHub Advisories · officialPublished Sep 25, 2026Risk 37/100

### Summary 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. ### Details The iframe assembled [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedService/EmbedHtmlFormatter.php#L204-L208) adds the url from `getUrl()` as the src without sanitization. The id regex for the archiveorg service and the url regexes for the wistia and sharepoint services allow for double quotes to be introduced. ### PoC Using double quotes, the src attribute can be escaped. ``` <embedvideo service="archiveorg" id='a" onmouseover="alert(document.domain)" data-x="'></embedvideo> ``` ### Impact When $wgEmbedVideoRequireConsent = false, any user able to edit a page can inject arbitrary JavaScript into an HTML event handler attribute (e.g. onfocus) via parameter. It requires no interaction (autofires via autofocus) and executes in the wiki origin for every visitor to the page.

Upgrade affected packages to a patched version: starcitizenwiki/embedvideo 4.1.0.

Vendor
Not specified
Product
starcitizenwiki/embedvideo
Exploitation
none known
Evidence
official
CVSS
7.5

This record is attributed to GitHub Advisories. Exploitation status and remediation guidance are kept separate from the vulnerability's technical severity.

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