jsPDF is a library to generate PDFs in JavaScript. Prior to 4.2.0, user control of the argument of the `addJS` method allows an attacker to inject arbitrary PDF objects into the generated document. By crafting a payload that escapes the JavaScript string delimiter, an attacker can execute malicious actions or alter the document structure, impacting any user who opens the generated PDF. The vulnerability has been fixed in jspdf@4.2.0. As a workaround, escape parentheses in user-provided JavaScript code before passing them to the `addJS` method.