estree-util-value-to-estree converts a JavaScript value to an ESTree expression. When generating an ESTree from a value with a property named proto, valueToEstree would generate an object that specifies a prototype instead. This vulnerability is fixed in 3.3.3.
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.