PrettyLinks < 3.6.21 - Authenticated (Administrator+) SQL Injection via 's' Parameter

Description

The PrettyLinks – Affiliate Links, Link Branding, Link Tracking, Marketing and Stripe Payments Plugin plugin for WordPress is vulnerable to SQL Injection via the 's' (search) parameter on the Pretty Links listing page in all versions up to, and including, 3.6.20. This is due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query in the `search_links_table()` function. This makes it possible for authenticated attackers, with Administrator-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.