BigProf Online Invoicing System (OIS) through 2.6 has XSS that can be leveraged for session hijacking. An attacker can exploit the XSS vulnerability, retrieve the session cookie from the administrator login, and take over the administrator account via the Name field in an Add New Client action.

PayPal Invoicing does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.

Unspecified vulnerability in netInvoicing before 2.7.3 has unknown impact and attack vectors, related to "security check soap".