EmbedVideo Extension : Stored XSS via unsanitized class passed to template
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- High · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
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, EmbedHtmlFormatter::toHtml in includes/EmbedService/EmbedHtmlFormatter.php passes the user-supplied class value directly to sprintf while constructing a figure element. A quote in the class value can terminate the class attribute and inject arbitrary HTML attributes or markup into the rendered page. A user able to edit a wiki page can store JavaScript that executes for visitors who render the affected content. This issue is fixed in version 4.1.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| StarCitizenWiki | mediawiki-extensions-EmbedVideo | before 4.1.0 | 4.1.0 | Patch available | CNA |
| — | starcitizenwiki/embedvideo (Packagist) | before 4.1.0 | 4.1.0 | Patch available | GHSA-7h5p-637f-jfr7 |
- mediawiki-extensions-EmbedVideo VendorStarCitizenWiki Affected before 4.1.0 Fixed in 4.1.0 Patch available CNA
- starcitizenwiki/embedvideo (Packagist) Vendor— Affected before 4.1.0 Fixed in 4.1.0 Patch available GHSA-7h5p-637f-jfr7
Remediation
- Fix · CNA mediawiki-extensions-EmbedVideo (StarCitizenWiki) Fixed in 4.1.0
- Fix · GHSA-7h5p-637f-jfr7 starcitizenwiki/embedvideo (Packagist) Fixed in 4.1.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55691
- 2026-10-03 Alias added: GHSA-7h5p-637f-jfr7
References
Other 4
- https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/security/advisories/GHSA-7h5p-637f-jfr7
- https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/commit/370156335b325bb81d14d89edf0a1f2643d50a84
- https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/releases/tag/v4.1.0
- https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo
More StarCitizenWiki vulnerabilities
- TI-2026-41377 Mediawiki EmbedVideo Extension has stored XSS via malformed src url with $wgEmbedVideoRequireConsent disabled CVSS 3.1HIGH 7.5
- TI-2026-40207 EmbedVideo Extension: Stored XSS via malformed src url with $wgEmbedVideoRequireConsent enabled CVSS 3.1HIGH 7.5
- TI-2026-40205 EmbedVideo Extension: Stored XSS via unsanitized service name in exception text CVSS 3.1HIGH 7.5
Sources
- CVE-2026-55691 · CVE Program
- CVE-2026-55691 · NVD
- FIRST EPSS
- GHSA-7h5p-637f-jfr7 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences