How severe is GHSA-mx3x-ghqm-r43h?

GHSA-mx3x-ghqm-r43h has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-mx3x-ghqm-r43h?

GHSA-mx3x-ghqm-r43h affects the following packages: predefine (npm). Ecosystems affected: npm.

How do I fix GHSA-mx3x-ghqm-r43h?

Update predefine to 0.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mx3x-ghqm-r43h is resolved across your whole dependency graph.

How do I detect GHSA-mx3x-ghqm-r43h in my npm dependencies?

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

How do I mitigate GHSA-mx3x-ghqm-r43h if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is GHSA-mx3x-ghqm-r43h actively exploited in the wild?

Yes. There are 1 known exploit references for GHSA-mx3x-ghqm-r43h, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-mx3x-ghqm-r43h?

GHSA-mx3x-ghqm-r43h has an EPSS (Exploit Prediction Scoring System) score of 3.1%, placing it in the 87th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-mx3x-ghqm-r43h published, and has it been updated?

GHSA-mx3x-ghqm-r43h was published on October 12, 2021 and was last updated on November 8, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

CRITICAL severity

Prototype pollution vulnerability in 'predefine'GHSA-mx3x-ghqm-r43h

CRITICALFix: bigpipe/predefine@1a86a01

GHSA-mx3x-ghqm-r43h is a critical-severity (CVSS 9.8) remote code execution vulnerability in predefine. 1 public exploit reference exists, so weaponization risk is real. A fix is available for predefine — see the affected versions and patch details below.

Also known asCVE-2020-28280

Published

Oct 12, 2021

Updated

Nov 8, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

3.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs87th percentile — riskier than 87% of all scored CVEsHighest risk

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

How urgent is this, really

GHSA-mx3x-ghqm-r43h 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

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.

10other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

predefinenpm

63Kdownloads / week

Description

Prototype pollution vulnerability in 'predefine' versions 0.0.0 through 0.1.2 allows an attacker to cause a denial of service and may lead to remote code execution.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`predefine`	all versions	0.1.3`npm install predefine@0.1.3`

Affected Products

1 product · 1 configurations

Application

predefinepredefine_project

≥ 0.0.0 && ≤ 0.1.2

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Prototype pollution vulnerability in 'predefine' versions 0.0.0 through …

github.comNVDDec 2020

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for predefine, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update predefine to 0.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mx3x-ghqm-r43h is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

Prototype pollution vulnerability in 'predefine' versions 0.0.0 through 0.1.2 allows an attacker to cause a denial of service and may lead to remote code execution.

O3 Security · Impact-Aware SCA

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