CVE-2020-1911 Explained : Impact and Mitigation

A type confusion vulnerability in Facebook Hermes prior to commit fe52854cdf6725c2eaa9e125995da76e6ceb27da can lead to arbitrary code execution through specially-crafted JavaScript.

Understanding CVE-2020-1911

What is CVE-2020-1911?

This CVE describes a type confusion vulnerability that arises when resolving properties of JavaScript objects with specially-crafted prototype chains in Facebook Hermes.

The Impact of CVE-2020-1911

The vulnerability can allow attackers to potentially execute arbitrary code by exploiting crafted JavaScript. However, it is only exploitable if the application using Hermes permits the evaluation of untrusted JavaScript, making most React Native applications unaffected.

Technical Details of CVE-2020-1911

Vulnerability Description

The vulnerability in Facebook Hermes, before the specified commit, can result in type confusion when processing JavaScript object properties, potentially enabling arbitrary code execution.

Affected Systems and Versions

Product: Hermes
Vendor: Facebook
Affected Version: commit prior to fe52854cdf6725c2eaa9e125995da76e6ceb27da

Exploitation Mechanism

Attackers exploit specially-crafted prototype chains in JavaScript objects within Hermes, leveraging the type confusion to execute arbitrary code.

Mitigation and Prevention

Immediate Steps to Take

Apply the patch provided by Facebook for Hermes to mitigate the vulnerability
Ensure that the application does not allow evaluation of untrusted JavaScript

Long-Term Security Practices

Regularly monitor and update the software components to include security patches
Implement secure coding practices to prevent similar vulnerabilities
Conduct security assessments and code reviews to identify and address weaknesses

Patching and Updates

Update Hermes to the version beyond commit fe52854cdf6725c2eaa9e125995da76e6ceb27da