CVE-2024-11582: Subscribe2 WordPress Plugin XSS Flaw

CVE-2024-11582 Overview

CVE-2024-11582 is a stored cross-site scripting (XSS) vulnerability in the Subscribe2 – Form, Email Subscribers & Newsletters plugin for WordPress. The flaw affects all versions up to and including 10.43. The plugin fails to properly sanitize and escape the ip parameter before storing and rendering it. Unauthenticated attackers can inject arbitrary JavaScript that executes when administrators or other users view affected pages. The issue is classified as [CWE-79] Improper Neutralization of Input During Web Page Generation.

Critical Impact
Unauthenticated attackers can inject persistent JavaScript into the WordPress admin interface, enabling session theft, administrative action hijacking, and redirection of site visitors.

Affected Products

Subscribe2 – Form, Email Subscribers & Newsletters plugin for WordPress
All versions up to and including 10.43
WordPress sites with the vulnerable plugin installed and active

Discovery Timeline

2025-02-19 - CVE-2024-11582 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-11582

Vulnerability Analysis

The Subscribe2 plugin stores subscriber IP addresses for record-keeping and administrative review. The ip parameter is captured during subscription events and later rendered in the plugin's list table view defined in class-s2-list-table.php. The plugin neither sanitizes the input at storage nor escapes it on output. An attacker can submit a crafted IP header value containing HTML or JavaScript payloads. When an administrator opens the subscriber list, the stored payload executes in the browser context of the WordPress admin session.

Root Cause

The vulnerability stems from missing input sanitization and missing output escaping in the subscriber list table rendering logic. The plugin reads the ip column value directly into HTML output without passing it through WordPress escaping functions such as esc_html() or esc_attr(). Attacker-controlled values flow from the HTTP request into persistent storage and then into the DOM unchanged.

Attack Vector

The attack requires no authentication and no user interaction beyond an administrator viewing the affected page. An attacker submits a subscription request while spoofing IP-related headers, such as X-Forwarded-For or Client-IP, with a JavaScript payload. The plugin stores this value as the subscriber IP. Each time a privileged user loads the subscriber management page, the script executes with that user's privileges, enabling actions such as creating administrator accounts, exfiltrating nonces, or modifying site content.

The vulnerability mechanism is described in the WordPress Plugin Code Review and the Wordfence Vulnerability Analysis.

Detection Methods for CVE-2024-11582

Indicators of Compromise

Subscriber records containing HTML tags such as <script>, <img>, <svg>, or onerror= in the IP address field
Unexpected outbound requests from administrator browsers to attacker-controlled domains shortly after viewing the Subscribe2 subscriber list
New administrator accounts or modified user roles created without authorized admin activity
Spoofed X-Forwarded-For or Client-IP headers containing non-IP content in web server access logs

Detection Strategies

Query the WordPress database for subscriber rows where the IP column contains characters outside the IPv4 or IPv6 format, such as <, >, or =
Inspect web server logs for subscription endpoint requests carrying forwarded IP headers with script-like payloads
Audit the Subscribe2 plugin version against the affected range and flag any installation at 10.43 or below

Monitoring Recommendations

Enable file integrity monitoring on the wp-content/plugins/subscribe2/ directory
Forward WordPress audit logs and web server access logs to a centralized analytics platform for correlation
Alert on creation of administrator accounts or changes to user capabilities outside expected change windows

How to Mitigate CVE-2024-11582

Immediate Actions Required

Update the Subscribe2 plugin to a version above 10.43 once a patched release is available from the vendor
If no patched version is available, deactivate and remove the Subscribe2 plugin from production WordPress sites
Review existing subscriber records and purge any entries containing HTML or JavaScript in the IP field
Rotate WordPress administrator passwords and invalidate active sessions if exploitation is suspected

Patch Information

At the time of writing, the vulnerability affects all versions up to and including 10.43. Site operators should monitor the plugin page on WordPress.org and the Wordfence Vulnerability Analysis advisory for patch availability and apply updates immediately upon release.

Workarounds

Deploy a web application firewall rule that blocks subscription requests containing HTML control characters in IP-related headers
Restrict access to the WordPress administrative interface by IP allow-list to limit who can render the vulnerable subscriber list page
Configure the web server to strip or normalize X-Forwarded-For and Client-IP headers from untrusted upstream sources

bash

# Example ModSecurity rule to block script payloads in forwarded IP headers
SecRule REQUEST_HEADERS:X-Forwarded-For "@rx (?i)(<script|onerror=|javascript:|<svg)" \
    "id:1011582,phase:1,deny,status:403,msg:'CVE-2024-11582 XSS payload in X-Forwarded-For'"