CVE-2023-6882 in Simple Membership Plugin
Summary
by MITRE • 01/11/2024
The Simple Membership plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the ‘environment_mode’ parameter in all versions up to, and including, 4.3.8 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages 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 • 04/11/2026
The Simple Membership plugin for WordPress represents a widely used authentication and membership management solution that has been identified with a critical reflected cross-site scripting vulnerability. This vulnerability affects all versions up to and including 4.3.8, creating a significant security risk for WordPress installations that rely on this plugin for user management and access control. The flaw resides in the plugin's handling of the 'environment_mode' parameter, which is processed without adequate input sanitization measures. This parameter is typically used to control the plugin's operational environment settings, but its improper handling creates an attack vector that can be exploited by malicious actors to inject malicious scripts into web pages.
The technical nature of this vulnerability stems from insufficient input validation and output escaping mechanisms within the plugin's codebase. When the 'environment_mode' parameter is passed through user input without proper sanitization, the plugin fails to encode or escape special characters that could be interpreted as executable script code. This allows attackers to craft malicious URLs containing script payloads that, when executed in a victim's browser, can perform unauthorized actions. The reflected nature of this XSS vulnerability means that the malicious script is reflected off the web server rather than being stored, making it particularly dangerous as it can be delivered through phishing emails, malicious links, or compromised websites that direct users to exploit the vulnerable parameter.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform a range of malicious activities that compromise user security and data integrity. Unauthenticated attackers can leverage this vulnerability to execute scripts that steal user session cookies, redirect victims to malicious websites, perform actions on behalf of logged-in users, or even install malware on affected systems. The vulnerability's accessibility to unauthenticated users makes it particularly dangerous since no prior authentication is required to exploit the flaw. This creates a significant risk for WordPress sites that host sensitive user information or require secure authentication mechanisms, as attackers can potentially escalate privileges or gain unauthorized access to user accounts through the execution of malicious scripts.
Organizations and WordPress administrators should prioritize immediate remediation of this vulnerability by updating to the latest version of the Simple Membership plugin where the XSS flaw has been addressed. The fix typically involves implementing proper input sanitization techniques and output escaping mechanisms for all user-supplied parameters. Security best practices recommend validating all input data against known safe character sets and encoding output data to prevent script execution. Additionally, implementing content security policies and using web application firewalls can provide additional layers of protection against similar vulnerabilities. This vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and represents a classic example of how insufficient input validation can create security risks that enable attackers to manipulate web applications and compromise user safety. The ATT&CK framework categorizes this as a web application vulnerability exploitation technique that can lead to session hijacking, credential theft, and privilege escalation attacks, making it a critical concern for cybersecurity professionals managing WordPress environments.