# Tinypool: Prototype Pollution gadget in worker options leads to Remote Code Execution

Advisory record · `GHSA-5gmw-xhrv-c9v3`

- **Identifiers:** `GHSA-5gmw-xhrv-c9v3` · `CVE-2026-104848`
- **State:** Confirmed
- **Severity:** CVSS 9.5 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-1321](https://cwe.mitre.org/data/definitions/1321.html)
- **Tags:** [Prototype pollution](https://agentprime.io/advisories/tag/prototype-pollution.md)
- **Published:** 5 Oct 2026
- **Updated:** 5 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 5 Oct 2026, 22:50 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.5: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `tinypool` (npm): affected `<2.1.1`; fixed in `2.1.1`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Tinypool versions before 2.1.1 pass worker options to Node's worker_threads.Worker by reading them through the prototype chain, so a prototype-pollution flaw elsewhere in an application's dependencies can inject options such as execArgv or env. An attacker who can pollute Object.prototype can then make pool workers load attacker-controlled code, gaining code execution with the host process's privileges. Upgrade tinypool to version 2.1.1 or later, which the advisory lists as the fixed version.

Written 31 Oct 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 9.5 Critical, CVSS 4.0: `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`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0050, the 43rd percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:34 UTC: First seen by agentprime
- 31 Oct 2026, 13:34 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-5gmw-xhrv-c9v3)

## Sources

- [GitHub Advisory Database: GHSA-5gmw-xhrv-c9v3](https://github.com/advisories/GHSA-5gmw-xhrv-c9v3)
- [OSV: GHSA-5gmw-xhrv-c9v3](https://osv.dev/vulnerability/GHSA-5gmw-xhrv-c9v3)
- <https://github.com/tinylibs/tinypool/security/advisories/GHSA-5gmw-xhrv-c9v3>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-104848>
- <https://github.com/tinylibs/tinypool/pull/134>
- <https://github.com/tinylibs/tinypool/commit/24df4e730e7d0857a6d226c9b58f8924227404fd>
- <https://github.com/tinylibs/tinypool>
- <https://github.com/tinylibs/tinypool/releases/tag/v2.1.1>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-5gmw-xhrv-c9v3>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-5gmw-xhrv-c9v3/>. Everything for agents: <https://agentprime.io/llms.txt>.