# Tinypool: Prototype Pollution Gadget to RCE in run() options Advisory record · `GHSA-85c8-ppgw-ccpr` - **Identifiers:** `GHSA-85c8-ppgw-ccpr` · `CVE-2026-104849` - **State:** Confirmed - **Severity:** CVSS 9.5 Critical - **Critical:** Yes: CVSS 9+ - **Weakness (CWE):** [CWE-94](https://cwe.mitre.org/data/definitions/94.html) · [CWE-1321](https://cwe.mitre.org/data/definitions/1321.html) - **Tags:** [Code injection](https://agentprime.io/advisories/tag/code-injection.md) · [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, 22:49 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: ## Affected packages - `tinypool` (npm): affected `<2.1.2`; fixed in `2.1.2` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > Tinypool versions before 2.1.2 are affected. When a caller passes an options object to pool.run(), the filename option is read through the prototype chain, so an attacker who can pollute Object.prototype with a filename property can make tinypool load and run an attacker-controlled worker module. Exploitation requires that prototype pollution exists elsewhere in the application and that the application passes an options object to run(); the attacker can then redirect task data to a malicious worker. Upgrade to tinypool 2.1.2 or later, which contains the fix. 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:** 0.0049, the 42nd percentile, on 9 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-85c8-ppgw-ccpr) ## Sources - [GitHub Advisory Database: GHSA-85c8-ppgw-ccpr](https://github.com/advisories/GHSA-85c8-ppgw-ccpr) - [OSV: GHSA-85c8-ppgw-ccpr](https://osv.dev/vulnerability/GHSA-85c8-ppgw-ccpr) - - - - - - 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 (), 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: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .