CVE-2021-3138 in Discourse
Summary
by MITRE • 01/14/2021
In Discourse 2.7.0 through beta1, a rate-limit bypass leads to a bypass of the 2FA requirement for certain forms.
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Analysis
by VulDB Data Team • 06/25/2024
The vulnerability identified as CVE-2021-3138 affects Discourse versions 2.7.0 through beta1 and represents a significant security flaw that undermines the platform's authentication mechanisms. This issue manifests as a rate-limit bypass that allows unauthorized users to circumvent two-factor authentication requirements for specific forms within the application. The vulnerability stems from improper implementation of rate-limiting controls that should have enforced strict authentication protocols before permitting access to sensitive functions.
The technical flaw lies in the application's failure to properly enforce rate-limiting mechanisms that would normally restrict the number of authentication attempts within a given time frame. When these controls are bypassed, attackers can exploit the system to make repeated authentication requests without proper verification, effectively disabling the two-factor authentication layer that should have been mandatory for certain critical forms. This weakness creates a window of opportunity for malicious actors to gain unauthorized access to protected resources while avoiding the additional security layer that 2FA typically provides.
From an operational impact perspective, this vulnerability significantly weakens the security posture of Discourse installations by allowing potential attackers to bypass critical authentication controls. The bypass affects the integrity of the authentication process and undermines user trust in the platform's security measures. Organizations relying on Discourse for community management, forums, or collaborative platforms face increased risk of unauthorized access to sensitive data, user accounts, and administrative functions. The vulnerability particularly impacts scenarios where users are required to verify their identity through multiple authentication factors, as the bypass renders these protections ineffective.
The security implications of this vulnerability align with CWE-305 authentication bypass weaknesses and can be categorized under ATT&CK technique T1212, which involves exploitation of application vulnerabilities to bypass security controls. Organizations should implement immediate mitigations including applying the vendor-provided security patches, reviewing and strengthening rate-limiting configurations, and monitoring for suspicious authentication patterns. Additional protective measures include implementing enhanced monitoring for unusual authentication behavior, conducting security audits of authentication flows, and ensuring proper enforcement of multi-factor authentication requirements across all critical application functions. The vulnerability serves as a reminder of the critical importance of proper rate-limiting implementation and the potential consequences when these controls fail to properly enforce security policies.