All versions of the package mockjs are vulnerable to Prototype Pollution via the Util.extend function due to missing check if the attribute resolves to the object prototype. 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 software depends on existence or non-existence of certain attributes, or uses pre-defined attributes of object prototype (such as hasOwnProperty, toString or valueOf).

User controlled inputs inside the extend() method of the Mock.Handler, Mock.Random, Mock.RE.Handler or Mock.Util, will allow an attacker to exploit this vulnerability.

Workaround

By using a denylist of dangerous attributes, this weakness can be eliminated.

Add the following line in the Util.extend function:

js
js if (["__proto__", "constructor", "prototype"].includes(name)) continue


js
// src/mock/handler.js
Util.extend = function extend() {
var target = arguments[0] || {},
i = 1,
length = arguments.length,
options, name, src, copy, clone

if (length === 1) {
target = this
i = 0
}

for (; i < length; i++) {
options = arguments[i]
if (!options) continue

for (name in options) {
if (["__proto__", "constructor", "prototype"].includes(name)) continue
src = target[name]
copy = options[name]

if (target === copy) continue
if (copy === undefined) continue

if (Util.isArray(copy) || Util.isObject(copy)) {
if (Util.isArray(copy)) clone = src && Util.isArray(src) ? src : []
if (Util.isObject(copy)) clone = src && Util.isObject(src) ? src : {}

target[name] = Util.extend(clone, copy)
} else {
target[name] = copy
}
}
}

return target
}
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

No history.

cve-icon MITRE

Status: PUBLISHED

Assigner: snyk

Published:

Updated: 2024-08-02T11:39:06.604Z

Reserved: 2023-02-20T10:28:48.930Z

Link: CVE-2023-26158

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2023-12-08T05:15:07.870

Modified: 2024-11-21T07:50:54.213

Link: CVE-2023-26158

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.