high · 7.5 Patched

StarCitizenWiki Extension Embed Video: Stored XSS via unsanitized service name in exception text

CVE-2026-55690 · GHSA-c29q-5xm7-5p62 · published 19 Jun 2026

How serious is it

  • Severity: high, CVSS score 7.5 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2026-55690?

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Who is affected

  • starcitizenwiki/embedvideo (Packagist) <= 4.0.0

How to check

  1. Run composer show starcitizenwiki/embedvideo in your project to see the installed version, including copies pulled in by other packages.
  2. Or paste your lockfile into the checker: it lists every package with a known vulnerability, this one included.

How to fix

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  1. Upgrade starcitizenwiki/embedvideo to 4.1.0 or later, commit the lockfile and redeploy.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

### Summary When passing an unknown service name to embedvideo, an error message is rendered containing the invalid service name. The service name is not sanitized and can contain HTML. ### Details There is a hardcoded list of allowed services in a switch statement inside `EmbedServiceFactory#newFromName` [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedService/EmbedServiceFactory.php#L105). When the service name is not known, an exception is thrown with the service name injected into the message via sprintf [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedService/EmbedServiceFactory.php#L286). This message is not sanitized and is marked as isHtml [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedVideo.php#L303-L311). Similarly with `{{evl:` [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedVideo.php#L177-L183). ### PoC ``` // Must be on a page, not on ExpandTemplates {{#ev:<img src=x onerror=alert(document.domain)>|dQw4w9WgXcQ}} {{#evl:id=dummy|service=<img src=x onerror=alert(document.domain)>}} ``` ### Impact Stored XSS that allows arbitrary Javascript/HTML insertion on any page that a user can edit. It requires no interaction and executes in the wiki origin for every visitor to the page.

Check your whole app

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References

Merged from GitHub Advisory Database. Last updated 23 Oct 2026. All vulnerabilities · RSS · JSON

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