yargs-parser Vulnerable to Prototype PollutionGHSA-p9pc-299p-vxgp
MEDIUMFix: yargs/yargs-parser@1c417bdGHSA-p9pc-299p-vxgp is a medium-severity (CVSS 5.3) CWE-1321 vulnerability in yargs-parser. 1 public exploit reference exists, so weaponization risk is real. A fix is available for yargs-parser — see the affected versions and patch details below.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-p9pc-299p-vxgp by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
yargs-parsernpmDescription
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | yargs-parser | ≥ 6.0.0&&< 13.1.2 | 13.1.2npm install yargs-parser@13.1.2 |
| 📦npm | yargs-parser | ≥ 14.0.0&&< 15.0.1 | 15.0.1npm install yargs-parser@15.0.1 |
| 📦npm | yargs-parser | ≥ 16.0.0&&< 18.1.1 | 18.1.1npm install yargs-parser@18.1.1 |
| 📦npm | yargs-parser | all versions | 5.0.1npm install yargs-parser@5.0.1 |
Affected Products
yargs-parseryargsResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yargs-parser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update yargs-parser to 13.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-p9pc-299p-vxgp is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | nodejs:12-8030020201124152102.229f0a1c | RHSA-2020:5499 |
| Red Hat Enterprise Linux 8 | nodejs:10-8030020210118191659.229f0a1c | RHSA-2021:0548 |
| Red Hat OpenShift Container Storage 4.7.0 on RHEL-8 | ocs4/mcg-core-rhel8:5.7.0-60.2c1fdb0.5.7 | RHSA-2021:2041 |
| Red Hat Quay 3 | quay/quay-rhel8:v3.6.0-62 | RHSA-2021:3917 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | rh-nodejs12-nodejs-0:12.19.1-2.el7 | RHSA-2020:5305 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | rh-nodejs10-nodejs-0:10.23.1-2.el7 | RHSA-2021:0521 |
Frequently Asked Questions
Is GHSA-p9pc-299p-vxgp in your dependencies?
Find it across npm, including transitive dependencies.