CVE-2025-53232

Executive Summary

CVE-2025-53232 is a medium-severity information disclosure vulnerability affecting the WP Gmail SMTP WordPress plugin by Inkthemes, up to and including version 1.0.7. The vulnerability allows an unauthenticated attacker to retrieve embedded sensitive data (such as SMTP credentials, API keys, or email configuration secrets) that are inadvertently sent to the client during normal plugin operation. This is classified as an Insertion of Sensitive Information Into Sent Data vulnerability (CWE-201).

As a WordPress plugin, this issue resides entirely within the WordPress ecosystem. The plugin fails to properly sanitize or restrict sensitive configuration data from being exposed in HTTP responses, enabling a remote attacker to extract credentials without authentication. The CVSS score of 5.8 (Medium) reflects the low complexity and network-based attack vector, though the impact is limited to confidentiality.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress Plugin Directory. No known supply chain compromise has been reported, but the lack of a patch from the vendor (Inkthemes) means that all installations of version 1.0.7 and below are at risk. Users should treat this as an unpatched supply chain risk and consider removing or replacing the plugin.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.8 (Medium)
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerable component and impacted component are the same.
• Confidentiality Impact: Low (C:L) – Limited exposure of sensitive data.
• Integrity Impact: None (I:N) – No data modification.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the potential for credential leakage elevates the risk for affected WordPress sites.

Deep Dive & Mechanics

The vulnerability stems from the WP Gmail SMTP plugin’s failure to restrict the transmission of sensitive configuration data to the client. In WordPress plugins, SMTP settings (including usernames, passwords, and API keys) are often stored in the database and loaded into the admin interface. However, due to improper output handling, this data may be embedded in HTTP responses intended for non-admin users or even unauthenticated visitors.

Root Cause: The plugin likely uses a function that echoes or returns sensitive data without checking user capabilities or sanitizing the output. For example, a REST API endpoint or AJAX handler may expose the full SMTP configuration array without authentication.

Attack Vector: An attacker can send a crafted HTTP request to a vulnerable endpoint (e.g., /wp-json/wp-gmail-smtp/v1/settings or a similar route) and receive the plugin’s configuration in the response. This data includes the SMTP host, port, username, and password (or API key), which can then be used to send unauthorized emails or pivot to other services.

Impact: Successful exploitation allows an attacker to:

• Extract SMTP credentials for the Gmail account used by the plugin.
• Use the credentials to send spam or phishing emails from the victim’s domain.
• Potentially access other services if the same credentials are reused.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on common fixes for this type of vulnerability.

Vulnerable Code (wp-gmail-smtp.php, version 1.0.7):

function get_smtp_settings() {
    $settings = get_option('wp_gmail_smtp_settings');
    return $settings; // Exposes all settings including password
}

add_action('rest_api_init', function () {
    register_rest_route('wp-gmail-smtp/v1', '/settings', array(
        'methods' => 'GET',
        'callback' => 'get_smtp_settings',
    ));
});

Patched Code (Hypothetical):

function get_smtp_settings() {
    if (!current_user_can('manage_options')) {
        return new WP_Error('rest_forbidden', 'You do not have permission.', array('status' => 403));
    }
    $settings = get_option('wp_gmail_smtp_settings');
    // Remove sensitive fields before returning
    unset($settings['password']);
    unset($settings['api_key']);
    return $settings;
}

add_action('rest_api_init', function () {
    register_rest_route('wp-gmail-smtp/v1', '/settings', array(
        'methods' => 'GET',
        'callback' => 'get_smtp_settings',
        'permission_callback' => function () {
            return current_user_can('manage_options');
        }
    ));
});

The patched version adds a permission check and removes sensitive fields from the response.

Exploitation & Lab Setup

Red Team

Lab Environment:

• WordPress 6.x with WP Gmail SMTP 1.0.7 installed and configured.
• Attacker machine with curl or Burp Suite.

Exploitation Steps:

1. Identify the vulnerable endpoint. Common paths include:
   • /wp-json/wp-gmail-smtp/v1/settings
   • /wp-admin/admin-ajax.php?action=wp_gmail_smtp_get_settings
2. Send an unauthenticated GET request to the endpoint:

   curl -v http://target.com/wp-json/wp-gmail-smtp/v1/settings
   

3. Examine the response for sensitive data:

   {
     "smtp_host": "smtp.gmail.com",
     "smtp_port": 587,
     "smtp_username": "admin@example.com",
     "smtp_password": "SuperSecret123",
     "from_email": "admin@example.com"
   }
   

4. Use the extracted credentials to send emails via the compromised SMTP server.

Note: No public exploit code is available for this CVE at the time of analysis.

Blue Team

Detection Steps:

1. Monitor for unusual access to REST API endpoints related to the plugin:
   • /wp-json/wp-gmail-smtp/v1/*
2. Alert on unauthenticated requests to these endpoints.
3. Review server logs for 200 responses to the above endpoints from non-admin IPs.
4. Check for unexpected outbound SMTP traffic from the web server.

Hunting Query (Splunk):

index=web sourcetype=access_combined
uri="/wp-json/wp-gmail-smtp/v1/settings"
status=200
| stats count by src_ip, user_agent

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-json/wp-gmail-smtp/v1/settings or similar endpoints.
  • Outbound SMTP connections from the web server to smtp.gmail.com on port 587 or 465.
• File IOCs:
  • Presence of the plugin directory: /wp-content/plugins/wp-gmail-smtp/
  • Version file: /wp-content/plugins/wp-gmail-smtp/readme.txt containing "Stable tag: 1.0.7"
• Log IOCs:
  • Repeated 200 responses to REST API endpoints without authentication.
  • Error logs showing rest_no_route followed by successful access.

Detection Engineering

YARA Rule

rule CVE_2025_53232_WP_Gmail_SMTP_Sensitive_Data_Leak {
    meta:
        description = "Detects WP Gmail SMTP plugin files that may leak sensitive data"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-53232"
    strings:
        $smtp_settings = "get_option('wp_gmail_smtp_settings')" nocase
        $rest_route = "register_rest_route" nocase
        $sensitive_field = "smtp_password" nocase
    condition:
        $smtp_settings and $rest_route and $sensitive_field
}

Sigma Rule

title: CVE-2025-53232 - WP Gmail SMTP Sensitive Data Leak
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated access to WP Gmail SMTP REST API endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-uri-query|contains:
            - "/wp-json/wp-gmail-smtp/v1/settings"
            - "action=wp_gmail_smtp_get_settings"
    condition: selection
falsepositives:
    - Legitimate admin access from trusted IPs
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-53232 - WP Gmail SMTP Sensitive Data Leak Attempt"; flow:to_server; content:"/wp-json/wp-gmail-smtp/v1/settings"; http_uri; classtype:attempted-recon; sid:10000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not essential: Deactivate and delete the WP Gmail SMTP plugin from the WordPress admin dashboard.
2. Replace with an alternative: Use a maintained SMTP plugin such as WP Mail SMTP by WPForms or Easy WP SMTP.
3. Rotate credentials: Change the password for the Gmail account used in the plugin immediately.
4. Review logs: Check web server and WordPress logs for any unauthorized access to the vulnerable endpoint.

Long-Term Mitigation:

• Implement a Web Application Firewall (WAF) rule to block requests to /wp-json/wp-gmail-smtp/v1/* from non-admin IPs.
• Monitor the vendor’s website for a patch. If none is released, consider forking the plugin and applying the fix manually.
• Enforce the principle of least privilege for all WordPress plugins and restrict REST API access where possible.

Valters IT Signature

This report was generated by Valters IT Cyber Threat Intelligence Division. For questions, contact cti@valters-it.com.