Jodit Editor is a WYSIWYG editor with written in pure TypeScript file and image editing capabilities. Versions prior to 4.12.26 are vulnerable to Prototype Pollution through Jodit.modules.Helpers.set(chain, value, obj), which walks the dot-separated chain, creating and following each path segment without filtering prototype-mutating keys. A chain that begins with (or contains) proto, constructor, or prototype lets the final assignment reach and mutate Object.prototype. Applications that pass a user-controlled or partially user-controlled key path into Jodit.modules.Helpers.set() could be vulnerable, causing unexpected property injection, logic bypass, denial of service, or secondary security issues. This issue has been fixed in version 4.12.26.