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New Prototype Pollution vulnerabilities in npm package

by Denis Makrushin

We discovered two more JS Prototype Pollution vulnerabilities in one more nmp-package: CVE-2020-28449, CVE-2020-28450. The package has ~200 weekly downloads, so the popularity level is limited. However, due to the patch is still unavailable check the details and make sure that your Node.js app is not affected.

You can find more interesting vulnerabilities and techniques of its finding and exploitation in our Bug Hunting Hub channel.

About Prototype Pollution

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_constructor and prototype.

An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

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