EmbedVideo Extension: Stored XSS via malformed src url with $wgEmbedVideoRequireConsent enabled

published 2026-06-19 4 mo ago modified 2026-09-30 39 d ago also GHSA-5c7p-g73q-rpg5 , EUVD-2026-78829

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits: 0; none known

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 the default $wgEmbedVideoRequireConsent configuration enabled, includes/EmbedService/EmbedHtmlFormatter.php places JSON returned through includes/EmbedService/AbstractEmbedService.php into the data-mw-iframeconfig attribute without safely escaping single quotes. Attacker-controlled archiveorg identifiers and wistia or sharepoint URLs accepted by the affected service validators can cause getUrl() output to terminate the attribute and inject event-handler attributes into the generated figure element. A user able to edit a wiki page can store JavaScript that executes in the wiki origin when visitors render the page. This issue is fixed in version 4.1.0.

Patch / fix

fixed in 1 links 2

packagist starcitizenwiki/embedvideo 4.1.0

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 54 d ago (2026-09-15)

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/security/advisories/GHSA-5c7p-g73q-rpg5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	starcitizenwiki/embedvideo	<4.1.0	4.1.0

Affected products

StarCitizenWiki mediawiki-extensions-EmbedVideo

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-80 Improper Neutralization of Script-Related HTML Tags in a Web Page

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary