Versions of the package jsondiffpatch before 0.7.6 are vulnerable to Prototype Pollution via the jsondiffpatch.patch() and jsondiffpatch/formatters/jsonpatch.patch() APIs. An attacker can perform prototype pollution by supplying crafted delta or JSON Patch documents, as attacker-controlled property names and path segments are used to traverse and modify objects without restricting access to special properties like __proto__ or constructor.prototype, allowing modification of Object.prototype.
Versions of the package jsondiffpatch before 0.7.2 are vulnerable to Cross-site Scripting (XSS) via HtmlFormatter::nodeBegin. An attacker can inject malicious scripts into HTML payloads that may lead to code execution if untrusted payloads were used as source for the diff, and the result renderer using the built-in html formatter on a private website.