Your RSA-2048 keys break in 2030. Find every one of them before attackers do.
📦
📦 npm
Not in CISA KEV
CRITICAL severity

Prototype pollution in Merge-deepGHSA-r6rj-9ch6-g264

CRITICALFix: jonschlinkert/merge-deep@11e5dd5

GHSA-r6rj-9ch6-g264 is a critical-severity (CVSS 9.8) CWE-1321 vulnerability in merge-deep. A fix is available for merge-deep — see the affected versions and patch details below.

Also known asCVE-2021-26707
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk
0.59%1.19%1.80%2.40%1.1%1.9%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-r6rj-9ch6-g264 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

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.

330other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
merge-deepnpm
2.0Mdownloads / week

Description

The merge-deep library before 3.0.3 for Node.js can be tricked into overwriting properties of Object.prototype or adding new properties to it. These properties are then inherited by every object in the program, thus facilitating prototype-pollution attacks against applications using this library.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmmerge-deepall versions3.0.3npm install merge-deep@3.0.3

Affected Products

2 products · 2 configurations
Application
merge-deepmerge-deep_project
< 3.0.3
range
Application
e-series performance analyzernetapp
all

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for merge-deep, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update merge-deep to 3.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r6rj-9ch6-g264 is resolved across your whole dependency graph.

  3. 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.

Frequently Asked Questions

The merge-deep library before 3.0.3 for Node.js can be tricked into overwriting properties of Object.prototype or adding new properties to it. These properties are then inherited by every object in the program, thus facilitating prototype-pollution attacks against applications using this library.
O3 Security · Impact-Aware SCA

Is GHSA-r6rj-9ch6-g264 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works
Prototype pollution in Merge-deep (Critical 9.8)