phpMyFAQ before 4.1.2 contains a path traversal vulnerability in Client::deleteClientFolder that allows admins with INSTANCE_DELETE permission to delete arbitrary directories. Attackers can submit traversal sequences like https://../../../<path> in the client URL parameter to recursively delete directories outside the intended clientFolder scope.

Affected: Packagist: thorsten/phpmyfaq, Packagist: phpmyfaq/phpmyfaq

## Summary

`Client::deleteClientFolder()` in `phpmyfaq/src/phpMyFAQ/Instance/Client.php:583` takes a URL from the caller, strips the `https://` prefix, and passes the remainder to `Filesystem::deleteDirectory()` relative to the multisite `clientFolder`. No path-traversal validation runs. An admin with the `INSTANCE_DELETE` permission (a role short of SUPER_ADMIN) submits `https://../../../<path>` as the client URL and the server recursively deletes arbitrary directories under the web user's rights. Same pattern and reachability as GHSA-38m8-xrfj-v38x, which the project accepted at High severity three weeks earlier.

## Details

`phpmyfaq/src/phpMyFAQ/Instance/Client.php:583-591`:

```php public function deleteClientFolder(string $sourceUrl): bool { if (!$this->isMultiSiteWriteable()) { return false; }

$sourcePath = str_replace(search: 'https://', replace: '', subject: $sourceUrl); return $this->filesystem->deleteDirectory($this->clientFolder . $sourcePath); } ```

`str_replace` strips the scheme but does nothing about `../` segments. The concatenation `$this->clientFolder . $sourcePath` directly feeds the filesystem call, which traverses above `clientFolder` without complaint.

Callers feed the URL from the HTTP request body:

`phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/InstanceController.php:184`:

```php if (1 !== $instanceId && $client->deleteClientFolder($clientData->url) && $client->delete($instanceId)) { ```

`$clientData->url` comes…