---
title: "CVE-2026-104849: Tinypool: Prototype Pollution Gadget to RCE in run() options"
url: https://erroneo.us/security/cve/CVE-2026-104849/
description: "CVE-2026-104849 (tinypool (npm)): Tinypool is a minimal Node.js worker thread pool implementation. Prior to 2.1.2, Tinypool reads filename from a…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-10-02
date_modified: 2026-10-06
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-104849"
kev: false
cvss: 9.5
epss: 0.0039
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-104849: Tinypool: Prototype Pollution Gadget to RCE in run() options

**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 32: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 32% 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 tinypool (npm) < 2.1.2, fixed in 2.1.2 . Check your lockfile, including transitive dependencies.

## What it is

Tinypool is a minimal Node.js worker thread pool implementation. Prior to 2.1.2, Tinypool reads filename from a caller-supplied options object in pool.run(task, options) without requiring an own property, so a polluted Object.prototype.filename can replace the intended worker module. Applications are affected only when they pass their own second-argument options object to pool.run(); calls without that argument use the trusted default options object. An attacker who can first pollute the prototype can cause the worker pool to load attacker-selected JavaScript and can read or modify task data with the host process's privileges. This issue is fixed in version 2.1.2.

## Affected packages

- npm `tinypool` < 2.1.2 → fixed: 2.1.2

## Affected products (CVE record)

- tinylibs tinypool: < 2.1.2

## Severity

- GitHub_M CVSS 4.0: 9.5 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
- GitHub CVSS 4.0: 9.5 `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.39% probability of exploitation activity in the next 30 days; percentile 32.

## Sources

- [GitHub Advisory GHSA-85c8-ppgw-ccpr](https://github.com/advisories/GHSA-85c8-ppgw-ccpr)
- [CVE.org record CVE-2026-104849](https://www.cve.org/CVERecord?id=CVE-2026-104849)
- [NVD entry CVE-2026-104849](https://nvd.nist.gov/vuln/detail/CVE-2026-104849)
- [github.com](https://github.com/tinylibs/tinypool/security/advisories/GHSA-85c8-ppgw-ccpr)
- [github.com](https://github.com/tinylibs/tinypool/pull/135)
- [github.com](https://github.com/tinylibs/tinypool/commit/f41411a3e23324c674f35a19a3240f7a7c40ffbf)
- [github.com](https://github.com/tinylibs/tinypool/releases/tag/v2.1.2)

---
Source page: https://erroneo.us/security/cve/CVE-2026-104849/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt