A sensitive information exposure vulnerability exists in ArthurFiorette steam-trader 2.1.1. An unauthenticated attacker can send a request to the /users API endpoint to retrieve highly sensitive Steam account data, including the account username, password, identity secret, and shared secret. In addition, application logs expose authentication artifacts such as access tokens, refresh tokens, and session identifiers. This information allows an attacker to generate valid Steam Guard (2FA) codes, hijack authenticated sessions, and obtain full control over the affected Steam account, including unauthorized access to inventory and trading functionality. No fix is available because the repository is archived and no longer maintained.