Versions of the package spin.js before 3.0.0 are vulnerable to Cross-site Scripting (XSS) via the spin() function that allows a creation of more than 1 alert for each 'target' element. An attacker would need to set an arbitrary key-value pair on Object.prototype through a crafted URL achieving a prototype pollution first, before being able to execute arbitrary JavaScript in the context of the user's browser.
CWE-79