CVE-2026-6295 [MEDIUM] – The WP Optimizer plugin for WordPress is vulnerable to SQL Injection via the ‘s’ parameter

The WP Optimizer plugin for WordPress is vulnerable to SQL Injection via the ‘s’ parameter in all versions up to and including 2.5.0. This is due to an unsafe subquery-detection branch in the Query::parse_key_compare_field() method that, when the user-supplied value matches the regex ^[(s]*SELECTs+, wraps the value in parentheses and embeds it directly into the SQL string without any escaping or quoting. While the normal LIKE code path correctly uses esc_sql($wpdb->esc_like(…)) and wraps the value in single quotes, this branch completely bypasses those protections. Because the attack payload (SELECT …) contains no single quotes, WordPress’s wp_magic_quotes() provides no protection. This makes it possible for authenticated attackers with administrator-level access to inject arbitrary SQL subqueries — including time-based blind payloads — that can be used to extract sensitive information from the database.