CVE-2013-4660

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);

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

Kodem intelligence

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.

1. What is CVE-2013-4660? CVE-2013-4660 is a critical-severity improper input validation vulnerability in js-yaml (npm), affecting versions < 2.0.5. It is fixed in 2.0.5. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. Which versions of js-yaml are affected by CVE-2013-4660? js-yaml (npm) versions < 2.0.5 is affected.
3. Is there a fix for CVE-2013-4660? Yes. CVE-2013-4660 is fixed in 2.0.5. Upgrade to this version or later.
4. Is CVE-2013-4660 exploitable, and should I be worried? Whether CVE-2013-4660 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2013-4660 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2013-4660? Upgrade js-yaml to 2.0.5 or later.