---
title: "CVE-2026-102992: piscina: Prototype-pollution gadget in ThreadPool.options allows RCE via execArgv / loadBalancer / env"
url: https://erroneo.us/security/cve/CVE-2026-102992/
description: "CVE-2026-102992 (piscina (npm)): piscina is a node.js worker pool implementation. Prior to 4.9.4, 5.3.2, and 6.0.0-rc.5, Piscina stores ThreadPool.options…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-30
date_modified: 2026-10-01
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-102992"
kev: false
cvss: 9.2
epss: 0.00434
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-102992: piscina: Prototype-pollution gadget in ThreadPool.options allows RCE via execArgv / loadBalancer / env

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.4% , percentile 37: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 37% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes piscina (npm) >= 5.0.0, < 5.3.2, fixed in 5.3.2 ; piscina (npm) < 4.9.4, fixed in 4.9.4 ; piscina (npm) >= 6.0.0-rc.1, < 6.0.0-rc.5, fixed in 6.0.0-rc.5 . Check your lockfile, including transitive dependencies.

## What it is

piscina is a node.js worker pool implementation. Prior to 4.9.4, 5.3.2, and 6.0.0-rc.5, Piscina stores ThreadPool.options in src/index.ts as a plain object that inherits from Object.prototype. Applications with a separate prototype-pollution primitive can therefore supply inherited values for security-sensitive options that do not have own defaults. An inherited execArgv value is passed to the Node.js Worker constructor and can preload attacker-controlled code in worker threads, an inherited loadBalancer function can execute during task scheduling, and inherited env values can alter worker environments. This issue is fixed in versions 4.9.4, 5.3.2, and 6.0.0-rc.5.

## Affected packages

- npm `piscina` >= 5.0.0, < 5.3.2 → fixed: 5.3.2
- npm `piscina` < 4.9.4 → fixed: 4.9.4
- npm `piscina` >= 6.0.0-rc.1, < 6.0.0-rc.5 → fixed: 6.0.0-rc.5

## Affected products (CVE record)

- piscinajs piscina: < 4.9.4, >= 5.0.0, < 5.3.2, >= 6.0.0-rc.1, < 6.0.0-rc.5

## Severity

- GitHub_M CVSS 4.0: 9.2 `CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`
- GitHub CVSS 4.0: 9.2 `CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.43% probability of exploitation activity in the next 30 days; percentile 37.

## Sources

- [GitHub Advisory GHSA-67c8-pqhq-4rmx](https://github.com/advisories/GHSA-67c8-pqhq-4rmx)
- [CVE.org record CVE-2026-102992](https://www.cve.org/CVERecord?id=CVE-2026-102992)
- [NVD entry CVE-2026-102992](https://nvd.nist.gov/vuln/detail/CVE-2026-102992)
- [github.com](https://github.com/piscinajs/piscina/security/advisories/GHSA-67c8-pqhq-4rmx)
- [github.com](https://github.com/piscinajs/piscina/commit/0cb12fca37f526065b072592afe954574dcc656f)
- [github.com](https://github.com/piscinajs/piscina/commit/2f69f67159a0e48b38fd61fa4a91c2fdc19fff72)
- [github.com](https://github.com/piscinajs/piscina/commit/5be7bbb19e3787bb698862cd516121a578d690f7)
- [github.com](https://github.com/piscinajs/piscina/commit/bebbda255c2981cecddd36b171b94be2fd41c9a6)
- [github.com](https://github.com/piscinajs/piscina/releases/tag/v4.9.4)
- [github.com](https://github.com/piscinajs/piscina/releases/tag/v5.3.2)
- [github.com](https://github.com/piscinajs/piscina/releases/tag/v6.0.0-rc.5)

---
Source page: https://erroneo.us/security/cve/CVE-2026-102992/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt