CVE-2020-36715 in Login-Signup Popup Plugin
Summary
by MITRE • 06/07/2023
The Login/Signup Popup plugin for WordPress is vulnerable to authorization bypass due to missing capability checks on several functions in versions up to, and including, 1.4. This makes it possible for authenticated attackers to inject arbitrary web scripts into the plugin settings that execute if they can successfully trick a user into performing an action such as clicking on a link.
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Analysis
by VulDB Data Team • 07/05/2023
The Login/Signup Popup plugin for WordPress presents a critical authorization bypass vulnerability identified as CVE-2020-36715, affecting versions up to and including 1.4. This flaw resides in the plugin's insufficient capability validation mechanisms that fail to properly verify user permissions before executing sensitive operations. The vulnerability stems from the absence of proper access control checks within multiple functions, allowing authenticated attackers with minimal privileges to manipulate plugin settings and inject malicious code. The issue manifests when attackers leverage their authenticated status to perform actions that should be restricted to administrators or users with elevated privileges, creating a dangerous pathway for privilege escalation within the WordPress environment.
The technical implementation of this vulnerability demonstrates a classic lack of input sanitization and capability verification patterns that align with CWE-285, which addresses improper authorization within software systems. Attackers can exploit this weakness by injecting arbitrary web scripts into plugin configuration settings through authenticated sessions, typically requiring only standard user credentials rather than administrator-level access. The vulnerability operates through a combination of insufficient privilege checks and inadequate validation of user capabilities, enabling malicious actors to execute code within the context of other users' sessions. This authorization bypass represents a significant security flaw that violates fundamental principles of least privilege and proper access control enforcement that should be inherent in all WordPress plugins.
The operational impact of CVE-2020-36715 extends beyond simple code injection to encompass potential session hijacking, data manipulation, and privilege escalation within the affected WordPress installation. When successfully exploited, authenticated attackers can inject malicious scripts that execute whenever legitimate users interact with the plugin settings or view pages where the injected code is rendered. This creates a persistent threat vector that can be leveraged for various malicious activities including credential theft, data exfiltration, or further compromise of the WordPress environment. The vulnerability's exploitation requires only that an attacker can authenticate to the WordPress system, making it particularly dangerous as it can be exploited by users with relatively low privileges such as subscribers or contributors who normally should not have access to plugin configuration interfaces.
Security professionals should recognize this vulnerability as a manifestation of ATT&CK technique T1078 which covers legitimate credentials and T1548 which addresses abuse of privileges through malicious code injection. The recommended mitigations include immediate plugin updates to versions that address the authorization bypass, implementation of proper capability checks in all plugin functions that modify settings, and enforcement of strict access controls for administrative operations. Organizations should also consider implementing additional monitoring for unauthorized plugin modifications and establish regular security audits of WordPress installations to identify similar privilege escalation vulnerabilities. The vulnerability underscores the critical importance of proper capability validation and input sanitization in WordPress plugin development, particularly for functions that modify system configurations or handle user data, as outlined in WordPress plugin security guidelines and industry best practices for secure coding practices.