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Critical, CVSS 9.5amended

Tinypool: Prototype Pollution Gadget to RCE in run() options

CVE-2026-104849GHSA-85c8-ppgw-ccpr

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (tinypool 2.1.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm tinypool

    Affected
    < 2.1.2
    Fixed in
    2.1.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
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 · score source
EPSS
  • CVE-2026-104849: 0.48% estimated exploitation activity in the next 30 days; percentile 41.82 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

tinypool is a fork of piscina and inherited the same prototype-pollution surface. When pool.run(task, options) is called, the filename option is read from the provided options object. If that object does not have an own filename property, the lookup falls through to Object.prototype. An attacker who can pollute Object.prototype.filename (for example, via a vulnerable lodash.merge, qs.parse, or similar elsewhere in the application) can make tinypool load and execute an attacker-controlled worker module. This is the tinypool counterpart to the piscina root discovery GHSA-x9g3-xrwr-cwfg. pool.run(task) with no second argument is not affected, because kDefaultOptions.filename is null and the options object is not user-controlled. The exploit only triggers when the caller passes their own options object to pool.run(). Impact Arbitrary JavaScript execution in the worker pool. If the application passes attacker-controlled data as the run() task and also supplies a run() options object, the…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-85c8-ppgw-ccpr

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-85c8-ppgw-ccpr

  4. Revision 1 · created ·

    Published from ghsa record GHSA-85c8-ppgw-ccpr

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-104849

Advisory: Tinypool: Prototype Pollution Gadget to RCE in run() options
IDs: CVE-2026-104849, GHSA-85c8-ppgw-ccpr
Record: https://patchnext.com/advisories/cve-2026-104849 (revision 4, source checked 26 Oct 2026, 13:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tinypool 2.1.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm tinypool: affected < 2.1.2; fixed in 2.1.2

## Suggested inspection (read-only)
- `npm ls tinypool --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tinypool.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-85c8-ppgw-ccpr (GitHub-reviewed advisory GHSA-85c8-ppgw-ccpr lists affected ranges: npm tinypool >=0 <2.1.2)
- Verified: https://osv.dev/vulnerability/GHSA-85c8-ppgw-ccpr (OSV record GHSA-85c8-ppgw-ccpr lists affected ranges: npm tinypool >=0 <2.1.2 (fixed))

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