CVE-2024-53807: WP Mailster SQL Injection Vulnerability

CVE-2024-53807 Overview

CVE-2024-53807 is a blind SQL injection vulnerability in the WP Mailster plugin for WordPress, developed by brandtoss. The flaw affects all versions of wp-mailster up to and including 1.8.16.0. Improper neutralization of special elements in SQL commands [CWE-89] allows attackers to inject arbitrary SQL statements through user-supplied input. Exploitation requires no authentication and can be performed remotely over the network. Successful attacks compromise the confidentiality, integrity, and availability of the WordPress database backing affected sites.

Critical Impact

Unauthenticated remote attackers can extract sensitive data, modify records, or escalate to administrative access by inferring database contents through blind SQL injection payloads.

Affected Products

• WP Mailster plugin for WordPress (wp-mailster)
• All versions from initial release through 1.8.16.0
• WordPress sites running the brandtoss WP Mailster extension

Discovery Timeline

• 2024-12-06 - CVE-2024-53807 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2024-53807

Vulnerability Analysis

The vulnerability resides in the WP Mailster plugin's handling of user-supplied input that is concatenated into SQL queries without proper sanitization or parameterization. Because the injection is blind, attackers do not receive direct query output. Instead, they infer database contents using boolean-based or time-based payloads that change application response behavior. The flaw is exploitable over the network with no authentication and no user interaction. WordPress installations using wp-mailster for newsletter and email campaign management expose subscriber data, administrator credentials, and arbitrary tables in the WordPress database to extraction.

Root Cause

The root cause is improper neutralization of special characters in SQL command construction [CWE-89]. The plugin builds SQL statements by concatenating untrusted input rather than using prepared statements with bound parameters through the $wpdb->prepare() API provided by WordPress. As a result, characters such as single quotes, comments, and conditional clauses pass directly into the query interpreter.

Attack Vector

Attackers craft HTTP requests targeting the vulnerable plugin endpoint and embed SQL syntax in parameter values. The injection point accepts crafted input that alters the underlying query logic. Using boolean conditions or time-delay functions such as SLEEP(), an attacker enumerates database schema, exfiltrates rows from wp_users and wp_options, and recovers password hashes or session tokens. See the Patchstack WordPress Vulnerability Report for technical details.

Detection Methods for CVE-2024-53807

Indicators of Compromise

• HTTP requests to WP Mailster plugin endpoints containing SQL meta-characters such as ', --, UNION SELECT, or SLEEP(
• Unexpected database queries in MySQL slow query logs originating from the wp-mailster plugin path
• New or modified administrator accounts in the wp_users table without corresponding admin activity
• Outbound traffic from the WordPress host to attacker-controlled infrastructure following plugin requests

Detection Strategies

• Inspect web server access logs for anomalous query strings and POST bodies targeting /wp-content/plugins/wp-mailster/ resources
• Deploy a web application firewall with SQL injection signatures tuned for WordPress plugin parameters
• Enable MySQL general query logging on staging or audit-mode systems to identify malformed queries originating from the plugin
• Correlate authentication anomalies in WordPress with timing patterns consistent with blind SQL injection probing

Monitoring Recommendations

• Monitor for sustained low-and-slow request patterns that indicate time-based blind injection enumeration
• Alert on spikes in 500-series HTTP responses from the WP Mailster plugin endpoints
• Track creation of WordPress users with elevated capabilities outside change-management windows
• Forward WordPress and web server logs to a centralized analytics platform for correlation against known SQL injection payloads

How to Mitigate CVE-2024-53807

Immediate Actions Required

• Disable or remove the WP Mailster plugin until a fixed version is confirmed installed
• Restrict access to WordPress admin and plugin endpoints via IP allowlisting where feasible
• Rotate WordPress administrator passwords and invalidate active sessions
• Review the wp_users, wp_usermeta, and wp_options tables for unauthorized modifications

Patch Information

At the time of CVE publication, no patched release beyond 1.8.16.0 was referenced in the available advisory data. Site operators should consult the Patchstack WordPress Vulnerability Report for current fix status and upgrade once the vendor publishes a corrected build.

Workarounds

• Deploy a web application firewall rule blocking SQL meta-characters in requests to wp-mailster paths
• Place the WordPress site behind authentication or a reverse proxy that filters unauthenticated plugin requests
• Apply database least-privilege so the WordPress database user cannot read administrative tables it does not require
• Take a verified backup of the WordPress database before applying mitigations to support forensic review

# Example WAF rule (ModSecurity) blocking SQLi patterns to wp-mailster endpoints
SecRule REQUEST_URI "@contains /wp-content/plugins/wp-mailster/" \
  "chain,deny,status:403,id:1005307,msg:'Block SQLi attempts against WP Mailster (CVE-2024-53807)'"
  SecRule ARGS|REQUEST_BODY "@rx (?i)(union[\s/*]+select|sleep\s*\(|benchmark\s*\(|--\s|';)" "t:none"