The WP-Polls plugin for WordPress is vulnerable to SQL Injection via COOKIE in all versions up to, and including, 2.77.2 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries. Those queries are stored and results are not displayed to the attacker, which means they cannot be exploited to obtain any additional information about the database. However, a properly configured payload allows for the injection of malicious JavaScript resulting in Stored Cross-Site Scripting.
The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.