A vulnerability in corydolphin/flask-cors version 4.0.1 allows the `Access-Control-Allow-Private-Network` CORS header to be set to true by default, without any configuration option. This behavior can expose private network resources to unauthorized external access, leading to significant security risks such as data breaches, unauthorized access to sensitive information, and potential network intrusions.

corydolphin/flask-cors is vulnerable to log injection when the log level is set to debug. An attacker can inject fake log entries into the log file by sending a specially crafted GET request containing a CRLF sequence in the request path. This vulnerability allows attackers to corrupt log files, potentially covering tracks of other attacks, confusing log post-processing tools, and forging log entries. The issue is due to improper output neutralization for logs.

An issue was discovered in Flask-CORS (aka CORS Middleware for Flask) before 3.0.9. It allows ../ directory traversal to access private resources because resource matching does not ensure that pathnames are in a canonical format.