The expandArguments function in the database abstraction API in Drupal core 7.x before 7.32 does not properly construct prepared statements, which allows remote attackers to conduct SQL injection attacks via an array containing crafted keys.
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.