Vulnerability Details : CVE-2023-26158
Potential exploit
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
}
Products affected by CVE-2023-26158
- cpe:2.3:a:mockjs:mock.js:*:*:*:*:*:node.js:*:*
Exploit prediction scoring system (EPSS) score for CVE-2023-26158
0.06%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 27 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2023-26158
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
8.2
|
HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H |
3.9
|
4.2
|
NIST | |
8.2
|
HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H |
3.9
|
4.2
|
Snyk |
CWE ids for CVE-2023-26158
-
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.Assigned by:
- nvd@nist.gov (Primary)
- report@snyk.io (Secondary)
References for CVE-2023-26158
-
https://security.snyk.io/vuln/SNYK-JS-MOCKJS-6051365
Prototype Pollution in mockjs | CVE-2023-26158 | SnykExploit;Mitigation;Third Party Advisory
-
https://github.com/nuysoft/Mock/blob/00ce04b92eb464e664a4438430903f2de96efb47/dist/mock.js%23L721-L755
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