CVE-2025-49333 Overview
CVE-2025-49333 is a stored Cross-Site Scripting (XSS) vulnerability in the wp.insider Simple Membership plugin for WordPress. The flaw affects all versions of Simple Membership up to and including 4.6.3. The plugin fails to properly neutralize user-supplied input during web page generation, allowing an authenticated attacker with high privileges to inject persistent JavaScript payloads. The stored payload executes in the browser of any user who views the affected page, enabling session theft, privilege abuse, and phishing against site visitors and administrators.
Critical Impact
An authenticated attacker can inject persistent JavaScript into the WordPress site, which then executes in the browsers of visitors and administrators, leading to account compromise and further site takeover.
Affected Products
- wp.insider Simple Membership plugin for WordPress
- All versions from initial release through 4.6.3
- WordPress sites with the vulnerable plugin activated
Discovery Timeline
- 2025-06-06 - CVE-2025-49333 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-49333
Vulnerability Analysis
The vulnerability is classified under CWE-79, Improper Neutralization of Input During Web Page Generation. Simple Membership accepts input from an administrative interface without applying adequate output encoding or sanitization before rendering the value in HTML context. As a result, script content supplied by a privileged user is stored in the database and later served to clients as executable JavaScript.
Because the payload persists server-side, the attack triggers on every subsequent page load without further attacker interaction. The scope change in this issue means the injected script runs in a security context different from the vulnerable component, expanding its blast radius across the WordPress site.
Root Cause
The root cause is missing or insufficient contextual output escaping in one or more Simple Membership administrative fields. The plugin writes attacker-controlled values into HTML without invoking WordPress escaping helpers such as esc_html(), esc_attr(), or wp_kses(). Any HTML tags or event handlers supplied by the user survive the round-trip through storage and rendering.
Attack Vector
Exploitation requires network access to the WordPress administrative interface and an authenticated account with high privileges, along with user interaction to trigger the stored payload. An attacker who has compromised or obtained a privileged Simple Membership account submits a crafted value containing a <script> tag or an HTML attribute with a JavaScript event handler. The value is stored and rendered when another user, including administrators, visits the affected page.
No verified proof-of-concept code is published for this issue. Refer to the Patchstack vulnerability report for coordinated disclosure details.
// No verified exploit code is available for CVE-2025-49333.
// See the Patchstack advisory linked above for technical context.
Detection Methods for CVE-2025-49333
Indicators of Compromise
- Presence of <script> tags, onerror=, onload=, or javascript: URIs stored in Simple Membership database tables and options
- Unexpected outbound requests from administrator browsers to attacker-controlled domains after visiting membership pages
- New or modified WordPress administrator accounts created shortly after an admin visited a Simple Membership page
- Simple Membership plugin version at or below 4.6.3 installed on production WordPress sites
Detection Strategies
- Query the WordPress database for Simple Membership records containing HTML control characters such as <, >, or event handler substrings
- Enable and review Content Security Policy (CSP) violation reports for inline script executions on membership pages
- Inspect web server access logs for POST requests to Simple Membership admin endpoints followed by anomalous GET traffic to the same rendered pages
Monitoring Recommendations
- Monitor WordPress admin sessions for cookie exfiltration patterns and unexpected token reuse from new IP addresses
- Alert on plugin file changes and on creation of new administrator or membership-level accounts
- Track browser telemetry from privileged users for script execution originating from Simple Membership URLs
How to Mitigate CVE-2025-49333
Immediate Actions Required
- Update the Simple Membership plugin to a version released after 4.6.3 that addresses this issue
- Audit all Simple Membership records and settings for previously injected HTML or JavaScript and remove any malicious content
- Rotate credentials and session tokens for WordPress administrators and privileged Simple Membership accounts
- Review the user list for unauthorized privileged accounts created during the exposure window
Patch Information
The vendor tracks and remediates this issue through the Simple Membership plugin update channel. Consult the Patchstack vulnerability report for the fixed version and upgrade path. Apply the update through the WordPress plugin dashboard or via WP-CLI.
Workarounds
- Restrict access to the WordPress admin interface using IP allow-listing at the web server or WAF layer
- Deploy a Content Security Policy that disallows inline scripts on WordPress admin and membership pages
- Deactivate the Simple Membership plugin until an updated version is applied if patching cannot be completed immediately
# Update the Simple Membership plugin using WP-CLI
wp plugin update simple-membership
# Verify the installed version is above 4.6.3
wp plugin get simple-membership --field=version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
