A prototype pollution vulnerability exists in Strikingly CMS which can result in reflected cross-site scripting (XSS) in affected applications and sites built with Strikingly. The vulnerability exists because of Strikingly JavaScript library parsing the URL fragment allows access to the proto or constructor properties and the Object prototype. By leveraging an embedded gadget like jQuery, an attacker who convinces a victim to visit a specially crafted link could achieve arbitrary javascript execution in the context of the users browser.
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Strikingly | Strikingly | * | * |
By adding or modifying attributes of an object prototype, it is possible to create attributes that exist on every object, or replace critical attributes with malicious ones. This can be problematic if the product depends on existence or non-existence of certain attributes, or uses pre-defined attributes of object prototype (such as hasOwnProperty, toString or valueOf). This weakness is usually exploited by using a special attribute of objects called proto, constructor or prototype. Such attributes give access to the object prototype. This weakness is often found in code that assigns object attributes based on user input, or merges or clones objects recursively.