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
}
Metrics
Affected Vendors & Products
References
History
No history.
MITRE
Status: PUBLISHED
Assigner: snyk
Published: 2023-12-08T05:00:01.350Z
Updated: 2024-08-02T11:39:06.604Z
Reserved: 2023-02-20T10:28:48.930Z
Link: CVE-2023-26158
Vulnrichment
No data.
NVD
Status : Analyzed
Published: 2023-12-08T05:15:07.870
Modified: 2023-12-12T22:26:30.457
Link: CVE-2023-26158
Redhat
No data.