EmbedVideo Extension : Stored XSS via unsanitized class passed to template

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55691
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-15 17:17:22 UTC
Updated2026-09-16 16:17:10 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 8.6 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

EPSS: 0.002950000 probability, percentile 0.221530000 (date 2026-09-16)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
3.1CNADECLARED8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA StarCitizenWiki Mediawiki-extensions-EmbedVideo affected < 4.1.0 Not specified

References

ReferenceSourceLinkTags
github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/releases/tag/... [email protected] github.com
github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/security/advi... 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/commit/370156... [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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