CVE-2023-5237 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Memberlite Shortcodes WordPress plugin versions prior to 1.3.9. The vulnerability arises because the plugin fails to properly validate and escape certain shortcode attributes before rendering them on web pages. This improper handling allows users with a relatively low privilege level—specifically those assigned the Contributor role—to inject malicious scripts that are persistently stored and executed when viewed by higher-privileged users such as administrators. The vulnerability is classified under CWE-79, which pertains to improper neutralization of input during web page generation, leading to XSS. The CVSS v3.1 base score is 5.4 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), requiring low privileges (PR:L), user interaction required (UI:R), scope changed (S:C), and impacts on confidentiality and integrity (C:L/I:L) but no impact on availability (A:N). Exploitation involves tricking an admin or other high-privilege user into viewing a page containing the malicious shortcode payload, which then executes arbitrary JavaScript in their browser context. This can lead to session hijacking, privilege escalation, or unauthorized actions within the WordPress admin interface. No public exploits are currently known in the wild, and no official patches or updates are linked in the provided data, though the vulnerability is noted as fixed in version 1.3.9 or later. The plugin’s failure to sanitize shortcode attributes represents a significant risk vector, especially in multi-user WordPress environments where contributors can add content but are not fully trusted. Attackers exploiting this vulnerability could compromise site integrity and confidentiality by leveraging the trust relationship between contributors and administrators.

For European organizations using WordPress sites with the Memberlite Shortcodes plugin, this vulnerability poses a moderate risk. The ability for low-privilege users to execute stored XSS attacks against administrators can lead to credential theft, unauthorized administrative actions, and potential site defacement or data leakage. This is particularly impactful for organizations relying on WordPress for internal portals, membership sites, or content management where contributor roles are common. Compromise of admin accounts could lead to broader system compromise, data breaches, or disruption of services. Given the medium CVSS score and the requirement for user interaction, the threat is less severe than remote code execution vulnerabilities but remains significant in environments with multiple user roles and sensitive data. Additionally, the scope change in the CVSS vector indicates that the vulnerability affects components beyond the initially vulnerable plugin, potentially impacting the entire WordPress site’s security posture. European organizations in sectors such as media, education, and non-profits that commonly use WordPress and allow contributor roles are particularly at risk. The absence of known exploits in the wild suggests limited active targeting currently, but the ease of exploitation and common usage of WordPress plugins means this could change rapidly if weaponized.

1. Immediate upgrade of the Memberlite Shortcodes plugin to version 1.3.9 or later where the vulnerability is fixed. If an upgrade is not immediately possible, consider temporarily disabling the plugin to prevent exploitation. 2. Restrict the Contributor role permissions to prevent shortcode usage or content submission that includes shortcodes until the patch is applied. 3. Implement Web Application Firewall (WAF) rules to detect and block suspicious shortcode attribute patterns or script injections targeting the affected plugin. 4. Conduct a thorough audit of user-generated content for injected scripts or suspicious shortcode attributes, especially content submitted by contributors. 5. Educate administrators and high-privilege users to be cautious when reviewing content submitted by lower-privilege users, especially in the WordPress editor or front-end previews. 6. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts and reduce the impact of any successful XSS payloads. 7. Monitor logs for unusual administrative activity or login attempts that could indicate exploitation attempts. 8. Regularly review and minimize the number of users with contributor or higher roles to reduce the attack surface. 9. Use security plugins that provide XSS protection and input sanitization enhancements beyond default WordPress capabilities.