Critical

Deserialization Code Execution in js-yaml

Disclosed: 24.10.2017
Updated: 11.10.2026 10:22

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.

Affected software

Click a technology to see all vulnerabilities affecting it.

Platform	Package	Vulnerable versions	Fixed in
npm package	js-yaml	< 2.0.5	2.0.5

References

CVSS score -

Weakness (CWE): CWE-20
Platform: npm
Package: js-yaml
Disclosed: 24.10.2017
Updated: 11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-xxvw-45rp-3mj2 - CC BY 4.0

Vulnerability history: js-yaml

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (12) in the archive

Total entries: 12
First → latest: 10.2017 09.2026
Without a fix: 0
Exploited in attacks: 0

Severity breakdown

Critical 1
High 5
Medium 6

Disclosures per year

2017: 1
2018: 0
2019: 2
2020: 0
2021: 0
2022: 0
2023: 0
2024: 0
2025: 1
2026: 8

08.09.2026

js-yaml: maxTotalMergeKeys does not limit CPU use for empty merge sources

High · 7.5 CVE-2026-84375 >= 4.0.0, < 4.3.2, >= 3.0.0, < 3.15.2 4.3.2, 3.15.2
06.08.2026

JS-YAML: Quadratic CPU consumption in !!omap resolution (3.x and 4.x) — CVE-2026-59870 fix not backported

High · 7.5 ghsa-5p4m-2wfm-xmqj >= 4.0.0, < 4.3.1, >= 3.0.0, < 3.15.1 4.3.1, 3.15.1
24.07.2026

js-yaml: Exponential parsing time in flow collections leads to denial of service

High · 7.5 CVE-2026-73643 >= 5.0.0, < 5.2.2 5.2.2
20.07.2026

js-yaml: YAML merge-key chains can force quadratic CPU consumption

High · 7.5 CVE-2026-59869 >= 3.0.0, < 3.15.0, >= 4.0.0, < 4.3.0 3.15.0, 4.3.0
04.06.2019

Code Injection in js-yaml

High ghsa-8j8c-7jfh-h6hx < 3.13.1 3.13.1
24.10.2017

Deserialization Code Execution in js-yaml this entry

Critical CVE-2013-4660 < 2.0.5 2.0.5

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