CVE-2017-5537 in Weblate
Summary
by MITRE
The password reset form in Weblate before 2.10.1 provides different error messages depending on whether the email address is associated with an account, which allows remote attackers to enumerate user accounts via a series of requests.
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Analysis
by VulDB Data Team • 09/08/2020
The vulnerability described in CVE-2017-5537 represents a classic account enumeration flaw that significantly impacts the security posture of the Weblate application. This issue affects versions prior to 2.10.1 and stems from the password reset functionality's inconsistent error messaging behavior. The flaw enables attackers to determine whether specific email addresses are registered within the system by observing different response messages when attempting password resets for various email addresses. This type of information disclosure vulnerability directly violates security principles by providing attackers with actionable intelligence about valid user accounts.
The technical implementation of this vulnerability resides in the application's password reset form logic where the system differentiates between valid and invalid email addresses through distinct error messages. When an attacker submits a password reset request for an email address not associated with any account, the system returns one type of error message, whereas submitting a request for a valid email address triggers a different response. This differential response pattern creates a side-channel attack vector that allows for systematic account enumeration. The vulnerability aligns with CWE-200, which addresses information exposure, and specifically demonstrates poor error handling practices that inadvertently leak sensitive information about the system's state.
The operational impact of this vulnerability extends beyond simple account enumeration, as it provides attackers with the foundational information needed for subsequent attacks. Once valid email addresses are identified, attackers can leverage this information for targeted phishing campaigns, credential stuffing attacks, or social engineering initiatives. The vulnerability also enables automated account discovery processes that can systematically map out user bases, potentially leading to more sophisticated attacks such as brute force attempts against discovered accounts. This issue particularly affects web applications that handle user authentication and account management, making it a critical concern for systems managing sensitive user data. The attack pattern follows the reconnaissance phase of the kill chain and aligns with ATT&CK technique T1087.001 for account discovery, where adversaries gather information about valid accounts to facilitate further compromise.
Mitigation strategies for this vulnerability require implementing consistent error messaging across all account validation scenarios. The password reset functionality should return identical generic error messages regardless of whether the email address exists in the system. This approach eliminates the information leakage that enables enumeration attacks and follows the principle of least information disclosure. Organizations should also implement rate limiting and account lockout mechanisms to prevent automated enumeration attempts, while ensuring that all user-facing error messages are carefully crafted to avoid revealing system internals. The fix for CVE-2017-5537 required updating the Weblate application to version 2.10.1 or later, where the inconsistent error handling was corrected through proper implementation of uniform response messages for all password reset attempts. This vulnerability highlights the importance of security by design principles and demonstrates how seemingly minor implementation details can create significant security risks in authentication systems.