lunary-ai/lunary is vulnerable to an authentication issue due to improper validation of email addresses during the signup process. Specifically, the server fails to treat email addresses as case insensitive, allowing the creation of multiple accounts with the same email address by varying the case of the email characters. For example, accounts for 'abc@gmail.com' and 'Abc@gmail.com' can both be created, leading to potential impersonation and confusion among users.