CVE-2025-9489 in Membership Plugin
Summary
by MITRE • 09/09/2025
The The WP-Members Membership Plugin plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 3.5.4.2. This is due to the software allowing users to execute an action that does not properly validate a value before running do_shortcode. This makes it possible for authenticated attackers, with Subscriber-level access and above, to execute arbitrary shortcodes.
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Analysis
by VulDB Data Team • 09/09/2025
The WP-Members Membership Plugin for WordPress presents a critical security vulnerability classified as CVE-2025-9489, affecting all versions through 3.5.4.2. This vulnerability resides within the plugin's handling of shortcode execution mechanisms, creating a pathway for unauthorized code injection that can be exploited by attackers with relatively low privileges. The flaw manifests when the plugin processes user input without adequate validation of shortcode parameters, allowing malicious actors to manipulate the execution flow and inject arbitrary code into the WordPress environment.
The technical implementation of this vulnerability stems from improper input validation within the plugin's shortcode processing functions. Specifically, the software fails to sanitize user-provided shortcode values before executing the do_shortcode function, which is a core WordPress mechanism for processing shortcode tags. This validation gap creates a direct code execution vector where authenticated users with subscriber-level access or higher can craft malicious shortcode payloads that will be processed and executed within the WordPress environment. The vulnerability operates at the level of WordPress's shortcode API, making it particularly dangerous as it leverages legitimate WordPress functionality to bypass normal security controls.
From an operational perspective, this vulnerability poses significant risks to WordPress installations using the affected plugin version. An attacker with subscriber privileges can leverage this flaw to execute arbitrary shortcodes that may include malicious code, potentially leading to complete system compromise. The impact extends beyond simple code execution, as the attacker can manipulate the plugin's functionality to perform unauthorized actions such as user privilege escalation, data exfiltration, or the installation of backdoors. The vulnerability's severity is amplified by the fact that it requires minimal privileges to exploit, making it accessible to users who typically would not have access to more critical system functions.
Security professionals should consider this vulnerability in the context of CWE-79, which addresses cross-site scripting and code injection flaws, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The vulnerability demonstrates a clear path from initial access through privilege escalation to potential system compromise, making it a prime target for attackers seeking persistent access to WordPress installations. Organizations should prioritize immediate patching of the WP-Members plugin to version 3.5.5 or later, as this represents the first release that addresses the improper input validation issue. Additionally, administrators should implement network monitoring to detect suspicious shortcode execution patterns and consider restricting user privileges where possible to limit the potential impact of such vulnerabilities. The vulnerability underscores the critical importance of proper input validation in web applications, particularly in plugins that handle user-generated content or execute dynamic code within the WordPress ecosystem.