CVE-2021-25941

Overview

Prototype pollution vulnerability in 'deep-override' versions 1.0.0 through 1.0.1 allows an attacker to cause a denial of service and may lead to remote code execution.

Details

The NPM module `deep-override` can be abused by Prototype Pollution vulnerability since the function `override()` does not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or be able to manipulate the property which leads to Denial of Service or potentially Remote code execution.

PoC Details

The `override()` function accepts `rawArgs` as arguments. Due to the absence of validation on the values passed into the argument, an attacker can supply a malicious value by adjusting the value to include the `__proto__` property. Since there is no validation before assigning the property to check whether the assigned argument is the Object's own property or not, the property `polluted` will be directly assigned to the new object thereby polluting the Object prototype. Later in the code, if there is a check to validate `polluted` the valued would be substituted as "Yes! It's Polluted" as it had been polluted.

PoC Code

var deepOverride = require("deep-override")

var obj = {} console.log("Before : " + obj.polluted);

deepOverride(obj, JSON.parse('{ "__proto__": { "polluted": "Yes! Its Polluted" }}'));

console.log("After : " + {}.polluted);

Affected Environments

1.0.0 to 1.0.1

Prevention

Upgrade to version 1.0.2