CVE-2024-39211 is an information disclosure vulnerability identified in Kaiten version 57.128.8. The flaw allows remote attackers to enumerate valid user accounts by sending crafted POST requests to the login endpoint. Specifically, the login response includes a user_email field only if the submitted username corresponds to an existing account. This behavior creates a side-channel that leaks user existence information, enabling attackers to confirm valid usernames without authentication or user interaction. The vulnerability is classified under CWE-204, which pertains to information exposure through discrepancies in system behavior. The CVSS v3.1 base score is 5.3, reflecting medium severity, with attack vector network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and impact limited to confidentiality (C:L) without affecting integrity or availability. No patches or known exploits are currently available. This vulnerability can be leveraged to facilitate further attacks such as targeted phishing, password spraying, or brute force attempts by providing attackers with a verified list of valid user accounts.

The primary impact of CVE-2024-39211 is the unauthorized disclosure of valid user account information. While it does not directly compromise system integrity or availability, the ability to enumerate user accounts can significantly aid attackers in mounting more effective social engineering, phishing, or brute force attacks. Organizations relying on Kaiten 57.128.8 may face increased risk of credential-based attacks and targeted intrusions. The exposure of user existence information can also lead to privacy concerns and regulatory compliance issues, especially in sectors handling sensitive personal data. Although no known exploits are currently active, the vulnerability lowers the barrier for attackers to identify valid usernames, increasing the attack surface and potentially leading to subsequent compromise if combined with weak password policies or other vulnerabilities.

To mitigate CVE-2024-39211, organizations should implement the following specific measures: 1) Monitor for and apply any official patches or updates from Kaiten vendors as soon as they become available. 2) Modify login response behavior to avoid disclosing user existence information; for example, ensure that error messages and response fields are identical regardless of whether the username exists. 3) Implement rate limiting and IP throttling on login endpoints to reduce the feasibility of automated user enumeration attempts. 4) Employ multi-factor authentication (MFA) to reduce the risk of account compromise even if usernames are enumerated. 5) Conduct regular security assessments and penetration tests to detect similar information leakage issues. 6) Educate users about phishing risks and monitor for suspicious login attempts or brute force activity. 7) Consider deploying web application firewalls (WAFs) with rules designed to detect and block enumeration patterns. These targeted mitigations go beyond generic advice by focusing on response normalization, access controls, and layered defenses specific to the enumeration vector.