CVE-2025-57973: WP-Members Plugin Stored XSS Vulnerability

CVE-2025-57973 Overview

CVE-2025-57973 is a stored Cross-Site Scripting (XSS) vulnerability affecting the Chad Butler WP-Members plugin for WordPress. The flaw stems from improper neutralization of user-supplied input during web page generation, classified under [CWE-79]. All versions of WP-Members up to and including 3.5.4.2 are affected. An authenticated attacker with low privileges can inject persistent JavaScript payloads that execute in the browsers of users who view the affected content. Because the vulnerability has a scope change component, injected scripts can affect resources beyond the vulnerable component itself.

Critical Impact

Authenticated attackers can store malicious JavaScript in WordPress pages rendered by WP-Members, leading to session hijacking, credential theft, or administrative account takeover when privileged users view the affected content.

Affected Products

• Chad Butler WP-Members plugin for WordPress
• All versions from n/a through 3.5.4.2
• WordPress sites using WP-Members for member registration and login

Discovery Timeline

• 2025-09-22 - CVE CVE-2025-57973 published to NVD
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-57973

Vulnerability Analysis

The WP-Members plugin fails to properly sanitize or encode user-supplied input before rendering it in HTML output. This allows an attacker with authenticated low-privilege access to inject arbitrary JavaScript that is persistently stored by the application. When another user, including administrators, loads a page containing the stored payload, the script executes in the context of the victim's browser session on the WordPress site.

The vulnerability requires user interaction and has high attack complexity, which limits trivial mass exploitation. However, successful exploitation can compromise site integrity and user confidentiality, particularly through theft of session cookies or forged administrative actions.

Root Cause

The plugin does not apply adequate output encoding or input validation on specific user-controllable fields before echoing them into the generated HTML. This absence of neutralization enables script tags and event handler attributes supplied by the attacker to be interpreted as executable code by the browser.

Attack Vector

Exploitation occurs over the network against the WordPress site. An authenticated attacker with at least low-level privileges submits input containing a malicious script payload through an affected WP-Members input field. The payload is stored in the WordPress database and later rendered to any user who accesses the affected page or endpoint. See the Patchstack WP-Members XSS Vulnerability advisory for additional technical context.

No verified public proof-of-concept code is available for this issue.

Detection Methods for CVE-2025-57973

Indicators of Compromise

• WordPress database entries in WP-Members-related tables containing <script> tags, javascript: URIs, or inline event handlers such as onerror= and onload=.
• Outbound HTTP requests from administrator browsers to unexpected external domains following page views on member-related pages.
• Unauthorized creation of administrative accounts or modification of user roles shortly after an administrator visits a WP-Members page.

Detection Strategies

• Review the WordPress wp_posts, wp_postmeta, and WP-Members configuration tables for HTML or JavaScript content in fields that should contain plain text.
• Deploy a Web Application Firewall (WAF) rule set that inspects form submissions to WP-Members endpoints for script injection patterns.
• Correlate authenticated low-privilege user activity with subsequent anomalous administrator session behavior.

Monitoring Recommendations

• Enable WordPress audit logging to capture content updates and user profile changes made through WP-Members forms.
• Monitor browser Content Security Policy (CSP) violation reports for inline script execution on pages served by WP-Members.
• Alert on new or modified WordPress administrator accounts and unexpected plugin or theme file modifications.

How to Mitigate CVE-2025-57973

Immediate Actions Required

• Identify all WordPress installations running the WP-Members plugin and inventory the installed version.
• Restrict registration and content submission capabilities on WP-Members forms until the plugin is updated.
• Audit existing stored content for injected scripts and remove any malicious payloads before patching.

Patch Information

At the time of publication, the vulnerability affects WP-Members up to and including version 3.5.4.2. Site administrators should upgrade to a fixed release once available from the plugin maintainer. Consult the Patchstack advisory for the latest patch status and vendor guidance.

Workarounds

• Apply a virtual patch through a WordPress-aware WAF to block XSS payloads targeting WP-Members endpoints.
• Enforce a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins.
• Limit the roles permitted to submit content through WP-Members forms to reduce the attacker population.

# Configuration example: strict CSP header via .htaccess for WordPress
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self'"