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

> Prototype pollution in Tinypool allows attackers to inject code into worker threads via execArgv or env, leading to remote code execution.

- **Severity:** Critical 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Oct 2026
- **Updated:** 2 Oct 2026
- **Also known as:** GHSA-5gmw-xhrv-c9v3, MINI-395r-8rr8-28vv, MINI-6ppf-979g-65jp, MINI-9cc7-f84v-rp8w, MINI-mx77-52gw-3qqg, ROOT-APP-NPM-CVE-2026-104848

## What is CVE-2026-104848?

CVE-2026-104848 is a critical code injection vulnerability in tinylibs tinypool, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-104848?

2 open source packages ship an affected version, including tinypool.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `tinypool` | npm | All versions | 2.1.1 |
| `tinypool` | npm | All versions | 2.1.1 |

## How do I fix CVE-2026-104848?

Upgrade tinypool to 2.1.1 or later.

## Is CVE-2026-104848 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104848 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104848 and fix it if it is affected.

What it is: CVE-2026-104848 is a critical code injection vulnerability in tinylibs tinypool, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104848 exists.

Affected packages and fixed versions:
- tinypool (npm): affected all versions; fixed in 2.1.1
- tinypool (npm): affected all versions; fixed in 2.1.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-104848/ (Markdown: https://insights.sbomify.com/CVE-2026-104848/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104848
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104848
- OSV: https://osv.dev/vulnerability/CVE-2026-104848

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104848/
Summaries are generated and may contain mistakes; the official description above is the record.