InvoicePlane 1.5.11 doesn't have any rate-limiting for password reset and the reset token is generated using a weak mechanism that is predictable.
In InvoicePlane 1.5.11 a misconfigured web server allows unauthenticated directory listing and file download. Allowing an attacker to directory traversal and download files suppose to be private without authentication.
In InvoicePlane 1.5.11, the upload feature discloses the full path of the file upload directory.