CVE-2021-25973 in Publify
Summary
by MITRE • 11/02/2021
In Publify, 9.0.0.pre1 to 9.2.4 are vulnerable to Improper Access Control. “guest” role users can self-register even when the admin does not allow. This happens due to front-end restriction only.
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Analysis
by VulDB Data Team • 11/05/2021
The vulnerability identified as CVE-2021-25973 affects Publify versions 9.0.0.pre1 through 9.2.4 and represents a critical improper access control flaw that undermines the application's user management security model. This vulnerability specifically targets the registration process where users with the guest role can bypass administrative restrictions intended to prevent self-registration. The flaw stems from a frontend-only restriction mechanism that fails to implement proper server-side validation, creating a significant security gap in the application's access control implementation.
The technical nature of this vulnerability aligns with CWE-284, which describes improper access control scenarios where insufficient authorization checks allow unauthorized users to perform actions they should not be permitted to execute. In this case, the frontend restriction serves as a false sense of security that can be easily circumvented by malicious actors who understand basic web application behavior. The vulnerability exists because the application relies solely on client-side validation rather than implementing robust server-side access control mechanisms that would prevent unauthorized registration attempts regardless of frontend protections.
The operational impact of this vulnerability is substantial as it allows any user to potentially gain unauthorized access to the application's registration functionality, effectively bypassing administrative controls that should restrict who can become a registered user. This creates a pathway for unauthorized individuals to gain access to potentially sensitive application features or content that should be restricted to legitimate users only. The vulnerability particularly affects systems where administrators have explicitly disabled public registration but users can still self-register through the application's interface.
From an ATT&CK perspective, this vulnerability maps to T1078 which covers valid accounts and T1566 which involves social engineering techniques. The flaw enables adversaries to establish unauthorized accounts within the application, potentially leading to further exploitation opportunities including privilege escalation, data manipulation, or unauthorized access to protected resources. The vulnerability also represents a failure in the principle of least privilege, where users are granted more access than they should legitimately possess based on their role within the application's security model.
Mitigation strategies should focus on implementing proper server-side validation for all registration attempts, ensuring that administrative registration restrictions are enforced regardless of frontend state. Organizations should implement robust access control mechanisms that validate user permissions at multiple levels including API endpoints, server-side processing, and database operations. The fix should involve removing reliance on frontend-only restrictions and instead implementing comprehensive server-side validation that checks administrative settings before allowing any registration process to proceed. Additionally, proper logging and monitoring should be implemented to detect unauthorized registration attempts and alert administrators to potential security incidents.