{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.0.0"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "starcitizenwiki/embedvideo"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55691"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79",
      "CWE-80"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T21:15:03Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\nThe user supplied class value is fed directly into the sprintf call that creates HTML. You can add a quote to escape the class and then inject arbitrary html/javascript to the final output.\n\n### Details\nThe template [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedService/EmbedHtmlFormatter.php#L138) adds a figure with a class that is substituted in. This value is provided to sprintf [here](https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/a573a16d925ee0ea0d34b360856dc8ab0b88f822/includes/EmbedService/EmbedHtmlFormatter.php#L156), an unescaped version of the class supplied by the user.\n\n```\n$template = \u003c\u003c\u003cHTML\n    \u003cfigure class=\"%s\" data-service=\"%s\" %s %s\u003e\n        \u003cdiv class=\"embedvideo-wrapper\" %s\u003e%s%s%s\u003c/div\u003e%s\n    \u003c/figure\u003e\nHTML;\n```\n\n### PoC\nNote the double quote immediately following the single quote to escape the class attribute in the template:\n```\n\u003cyoutube class=\u0027\" onmouseover=\"alert(document.domain)\u0027 id=\"dQw4w9WgXcQ\"\u003edQw4w9WgXcQ\u003c/youtube\u003e\n```\n\n### Impact\nArbitrary HTML can be inserted into the DOM by any user on any page, allowing for JavaScript to be executed.",
  "id": "GHSA-7h5p-637f-jfr7",
  "modified": "2026-06-19T21:15:03Z",
  "published": "2026-06-19T21:15:03Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/security/advisories/GHSA-7h5p-637f-jfr7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/commit/370156335b325bb81d14d89edf0a1f2643d50a84"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo"
    },
    {
      "type": "WEB",
      "url": "https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/releases/tag/v4.1.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "StarCitizenWiki Extension Embed Video: Stored XSS via unsanitized class passed to template"
}