EmbedVideo Extension: Stored XSS via unsanitized service name in exception text

published 2026-06-19 4 mo ago modified 2026-09-30 39 d ago also EUVD-2026-78831 , GHSA-c29q-5xm7-5p62

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, 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.

Patch / fix

fixed in 2 links 2

packagist starcitizenwiki/embedvideo 4.1.0
star-citizen embedvideo 4.1.0

CISA SSVC

Exploitation: none
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).

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary