Invoice Ninja before 5.10.43 allows remote code execution from a pre-authenticated route when an attacker knows the APPKEY. This is exacerbated by .env files, available from the product's repository, that have default APPKEY values. The route/{hash} route defined in the invoiceninja/routes/client.php file can be accessed without authentication. The parameter {hash} is passed to the function decrypt that expects a Laravel ciphered value containing a serialized object. (Furthermore, Laravel contains several gadget chains usable to trigger remote command execution from arbitrary deserialization.) Therefore, an attacker in possession of the APPKEY is able to fully control a string passed to an unserialize function.

In Invoice Ninja before 4.4.0, there is an unsafe call to unserialize() in app/Ninja/Repositories/AccountRepository.php that may allow an attacker to deserialize arbitrary PHP classes. In certain contexts, this can result in remote code execution. The attacker's input must be hosted at http://www.geoplugin.net (cleartext HTTP), and thus a successful attack requires spoofing that site or obtaining control of it.

invoiceninja is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Invoice Ninja version 3.8.1 is vulnerable to stored cross-site scripting vulnerability, within the invoice creation page, which can result in disruption of service and execution of javascript code.