CVE-2019-3579 in MyBB
Summary
by MITRE
MyBB 1.8.19 allows remote attackers to obtain sensitive information because it discloses the username upon receiving a password-reset request that lacks the code parameter.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2019-3579 affects MyBB version 1.8.19 and represents a sensitive information disclosure flaw that can be exploited by remote attackers. This issue stems from the application's improper handling of password reset requests, specifically when the required code parameter is missing from the request. The vulnerability allows an attacker to extract username information without requiring authentication or valid session tokens, creating a significant security risk for user account security and privacy.
This technical flaw operates at the application logic level and can be categorized under CWE-200, which deals with information exposure. The vulnerability exists because the MyBB application does not properly validate the presence of required parameters in the password reset functionality. When an attacker submits a password reset request without providing the expected code parameter, the system inadvertently reveals the username associated with the request rather than properly rejecting the malformed request. This behavior violates fundamental security principles of least privilege and proper input validation.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with valuable reconnaissance data that can be used in subsequent attacks. An attacker can systematically test multiple usernames against the password reset endpoint to determine which accounts exist within the system, enabling targeted credential stuffing or brute force attacks. The vulnerability is particularly dangerous because it can be exploited without any prior authentication, making it a low-hanging fruit for attackers seeking to compromise user accounts. This type of vulnerability aligns with ATT&CK technique T1589.002, which involves acquiring access to information about users and accounts through reconnaissance activities.
The security implications of this vulnerability are significant as it undermines the confidentiality of user account information and can facilitate more sophisticated attack vectors. The disclosed username information can be used in combination with other attack techniques to compromise user accounts through social engineering or credential reuse attacks. Additionally, the vulnerability demonstrates poor input validation practices that could indicate broader security weaknesses within the application's authentication and authorization mechanisms. Organizations using MyBB version 1.8.19 should prioritize immediate remediation through patch updates, as the vulnerability provides attackers with direct access to user account information without requiring any privileged access or complex attack vectors. The flaw also highlights the importance of proper error handling and input validation in web applications, particularly in security-sensitive areas such as authentication and account recovery functions.