C5 Firefly III CSV Injection.

Summary

### Summary CSV injection is a vulnerability where untrusted user input in CSV files can lead to unauthorized access or data manipulation. In my subsequent testing of the application.

### Details I discovered that there is an option to "Export Data" from the web app to your personal computer, which exports a "csv" file that can be opened with Excel software that supports macros.

P.S I discovered that the web application's is offering a demo-site that anyone may access to play with the web application. So, there's a chance that someone will export the data (CVS) from the demo site and execute it on their PC, giving the malicious actor a complete control over their machine. (if a user enters a malicious payload to the website).

### PoC You can check out my vulnerability report if you need more details/PoC with screenshots: (removed by JC5)

### Impact An attacker can exploit this by entering a specially crafted payload to one of the fields, and when a user export the csv file using the "Export Data" function, the attacker can potentiality can RCE.

### Addendum by JC5, the developer of Firefly III There is zero impact on normal users, even on vulnerable versions.