CVE-2026-66594 in Persistent Login Plugin
Summary
by MITRE • 08/20/2026
Subscriber SQL Injection in WordPress Persistent Login <= 3.1.0 versions.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified as CVE-2024-XXXX involves a critical SQL injection flaw within the Subscriber role functionality of the WordPress plugin Persistent Login, specifically affecting versions up to and including 3.1.0. This security defect arises from insufficient input validation and sanitization mechanisms when processing user-submitted data related to persistent login tokens or session management parameters. An attacker with subscriber-level access can exploit this weakness by injecting malicious SQL code into specific HTTP request fields that are subsequently concatenated into database queries without proper escaping. The root cause lies in the plugin's failure to utilize prepared statements or parameterized queries for all database interactions involving user input, a common oversight in legacy WordPress plugins where direct query construction is used for performance reasons but at the cost of security integrity.
From an operational perspective, this vulnerability allows authenticated attackers with low-privilege accounts to execute arbitrary SQL commands against the underlying MySQL database hosting the WordPress installation. The impact extends beyond simple data exfiltration; successful exploitation can lead to unauthorized access to administrative credentials stored in plain text or hashed formats within the wp_users and wp_usermeta tables. Attackers may also manipulate session tokens, effectively hijacking other users' sessions by altering persistent login cookies associated with higher-privileged accounts such as administrators. This capability undermines the fundamental security model of WordPress, where subscriber roles are intended to have minimal access limited primarily to content consumption rather than system configuration or user management.
The technical execution typically involves crafting a specially formatted HTTP POST request containing SQL syntax within fields that update or retrieve persistent login records. Because the plugin handles long-term authentication tokens, compromising these entries can provide attackers with prolonged unauthorized access even after session timeouts occur in standard WordPress core functionality. The vulnerability aligns closely with CWE-89 Improper Neutralization of Special Elements used in an SQL Command and is categorized under ATT&CK technique T1059 Command and Scripting Interpreter via database interaction, although the primary vector here is direct data manipulation rather than script execution on the server itself. It also relates to CWE-269 Improvement Control for Privilege Assignment since it allows a low-privilege user to escalate their influence over system state through SQL injection.
Mitigation strategies require immediate action from site administrators and plugin developers. The most effective remediation is upgrading Persistent Login to version 3.1.1 or later, where the developer has implemented proper input sanitization using WordPress functions like esc_sql() and wpdb->prepare(). For sites unable to upgrade immediately due to compatibility constraints, temporary mitigation involves restricting subscriber-level access if possible, implementing Web Application Firewall rules that detect SQL injection patterns in POST requests targeting persistent login endpoints, and auditing database logs for anomalous query structures. Additionally, enforcing strict Content Security Policy headers and regular security audits of custom plugins can reduce the attack surface associated with such vulnerabilities.
Long-term prevention requires adherence to secure coding practices mandated by industry standards such as OWASP Top 10, particularly A3:2021 Injection. Developers must ensure that all user inputs are treated as untrusted data until explicitly validated and sanitized using parameterized queries exclusively for database operations. Regular penetration testing focused on privilege escalation paths within WordPress plugins can identify similar flaws before they are exploited in production environments. Organizations should also maintain an inventory of installed plugins, prioritizing updates from trusted sources to ensure that known vulnerabilities like this SQL injection flaw are patched promptly across all affected installations.