CVE-2025-14904: WordPress Newsletter Email Subscribe CSRF

CVE-2025-14904 Overview

The Newsletter Email Subscribe plugin for WordPress contains a Cross-Site Request Forgery (CSRF) vulnerability in versions up to and including 2.4. This security flaw stems from incorrect nonce validation on the nels_settings_page function, which allows unauthenticated attackers to manipulate plugin settings through forged requests. Successful exploitation requires social engineering to trick a site administrator into clicking a malicious link while authenticated.

Critical Impact

Unauthenticated attackers can modify plugin settings without authorization, potentially leading to newsletter system misconfigurations, unauthorized email campaigns, or further attack chain enablement.

Affected Products

• Newsletter Email Subscribe plugin for WordPress versions up to and including 2.4
• WordPress sites with vulnerable Newsletter Email Subscribe installations
• Sites where administrators may interact with untrusted links while logged in

Discovery Timeline

• 2026-01-07 - CVE CVE-2025-14904 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-14904

Vulnerability Analysis

This Cross-Site Request Forgery (CSRF) vulnerability exists due to improper implementation of WordPress security nonces in the plugin's settings page handler. The nels_settings_page function fails to properly validate nonce tokens, which are cryptographic values designed to verify the authenticity and intent of form submissions.

When a legitimate administrator accesses the plugin settings page, WordPress should generate a unique nonce that is validated upon form submission. However, the vulnerable code either omits this validation entirely or implements it incorrectly, allowing attackers to craft requests that bypass this protection mechanism.

Root Cause

The root cause is CWE-352 (Cross-Site Request Forgery) resulting from incorrect nonce validation in the nels_settings_page function located in newsletter-email-subscribe.php at line 109. The plugin fails to properly verify that settings modification requests originate from authorized administrative sessions with valid CSRF tokens.

In WordPress plugin development, nonce validation is typically implemented using wp_verify_nonce() or check_admin_referer() functions. The vulnerable implementation either omits these security checks or implements them improperly, creating the attack surface.

Attack Vector

The attack requires a network-based vector where an attacker crafts a malicious webpage or link containing a forged HTTP request to the plugin's settings endpoint. The attack scenario typically unfolds as follows:

1. Attacker identifies a target WordPress site using a vulnerable Newsletter Email Subscribe installation
2. Attacker creates a malicious page containing an auto-submitting form or JavaScript that triggers the settings modification request
3. Attacker entices an authenticated administrator to visit the malicious page via phishing, forum posts, or other social engineering tactics
4. When the administrator visits the malicious page, the forged request executes with the administrator's authenticated session
5. Plugin settings are modified without the administrator's knowledge or consent

The attack requires user interaction (clicking a link) but no privileges on the target system, making it accessible to unauthenticated attackers with social engineering capabilities.

Detection Methods for CVE-2025-14904

Indicators of Compromise

• Unexpected modifications to Newsletter Email Subscribe plugin settings without administrative action
• Web server logs showing POST requests to plugin settings endpoints from unusual referrers or external domains
• Changes to email subscriber lists, newsletter configurations, or SMTP settings without documented authorization
• Administrator sessions showing plugin settings access concurrent with external website visits

Detection Strategies

• Review WordPress activity logs for unauthorized settings changes to the Newsletter Email Subscribe plugin
• Monitor HTTP POST requests to /wp-admin/ paths containing newsletter email subscribe settings parameters
• Implement Content Security Policy (CSP) headers to restrict form submissions to trusted origins
• Use web application firewalls (WAF) to detect and block potential CSRF attack patterns

Monitoring Recommendations

• Enable WordPress audit logging plugins to track all plugin configuration changes
• Configure alerting for settings modifications occurring outside normal administrative workflows
• Monitor for newsletter-related configuration anomalies such as unauthorized SMTP server changes
• Implement browser-level protections like SameSite cookie attributes to limit cross-origin request capabilities

How to Mitigate CVE-2025-14904

Immediate Actions Required

• Update the Newsletter Email Subscribe plugin to a patched version beyond 2.4 when available
• Review current plugin settings to ensure no unauthorized modifications have occurred
• Advise WordPress administrators to avoid clicking untrusted links while logged into the admin dashboard
• Consider temporarily disabling the plugin until a security patch is released

Patch Information

Organizations should monitor the WordPress Plugin Repository and Wordfence Threat Intelligence for updates regarding patched versions. The fix should implement proper nonce validation using WordPress security functions such as wp_verify_nonce() or check_admin_referer() in the nels_settings_page function.

Workarounds

• Restrict administrative access to trusted networks using IP whitelisting or VPN requirements
• Implement additional authentication factors for WordPress administrative sessions
• Use browser extensions or security policies that isolate administrative sessions from general browsing
• Deploy a web application firewall with CSRF protection rules to add defense-in-depth

# WordPress .htaccess configuration to restrict admin access by IP
<Files wp-login.php>
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from YOUR.TRUSTED.IP.ADDRESS
</Files>

<Directory /wp-admin>
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from YOUR.TRUSTED.IP.ADDRESS
</Directory>