OpenRefine is a free, open source tool for working with messy data. Prior to version 3.8.3, lack of cross-site request forgery protection on the `preview-expression` command means that visiting a malicious website could cause an attacker-controlled expression to be executed. The expression can contain arbitrary Clojure or Python code. The attacker must know a valid project ID of a project that contains at least one row, and the attacker must convince the victim to open a malicious webpage. Version 3.8.3 fixes the issue.