In "I hate money" before version 4.1.5, an authenticated member of one project can modify and delete members of another project, without knowledge of this other project's private code. This can be further exploited to access all bills of another project without knowledge of this other project's private code. With the default configuration, anybody is allowed to create a new project. An attacker can create a new project and then use it to become authenticated and exploit this flaw. As such, the exposure is similar to an unauthenticated attack, because it is trivial to become authenticated. This is fixed in version 4.1.5.
CWE-863 - Incorrect Authorization
Authorization is a security mechanism performed by an application to grant or deny access to the requested resources by verifying the privileges of the user. When an application lacks effective authorization mechanisms, it enables unauthorized users to gain unintended privileges and illegitimate access to resources. Such a vulnerability may result in exposure of sensitive information, denial of service, arbitrary code execution, and complete system takeover.