CVE Vulnerabilities


Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Published: Jan 22, 2024 | Modified: Jan 30, 2024
CVSS 3.x
CVSS 2.x

hoolock is a suite of lightweight utilities designed to maintain a small footprint when bundled. Starting in version 2.0.0 and prior to version 2.2.1, utility functions related to object paths (get, set, and update) did not block attempts to access or alter object prototypes. Starting in version 2.2.1, the get, set and update functions throw a TypeError when a user attempts to access or alter inherited properties.


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.

Affected Software

Name Vendor Start Version End Version
Hoolock Elijahharry 2.0.0 *

Extended Description

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.

Potential Mitigations