Medium

yargs-parser Vulnerable to Prototype Pollution

  • Disclosed: 04.09.2020
  • Updated: 11.10.2026 10:22

Affected versions of yargs-parser are vulnerable to prototype pollution. Arguments are not properly sanitized, allowing an attacker to modify the prototype of Object, causing the addition or modification of an existing property that will exist on all objects.
Parsing the argument --foo.__proto__.bar baz' adds a bar property with value baz to all objects. This is only exploitable if attackers have control over the arguments being passed to yargs-parser.

Recommendation

Upgrade to versions 13.1.2, 15.0.1, 18.1.1 or later.

Affected software

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PlatformPackageVulnerable versionsFixed in
npm package yargs-parser >= 6.0.0, < 13.1.2, >= 14.0.0, < 15.0.1, >= 16.0.0, < 18.1.1, < 5.0.1 13.1.2, 15.0.1, 18.1.1, 5.0.1

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Weakness (CWE)
CWE-1321, CWE-915
Platform
npm
Package
yargs-parser
Disclosed
04.09.2020
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-p9pc-299p-vxgp - CC BY 4.0

Vulnerability history: yargs-parser

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

This is the only known vulnerability of this package.

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