# CVE-2026-110842: n8n before 2.41.4 and 2.42.1 Prototype Pollution via MCP Workflow-Validation Interpreter

> Authenticated users can exploit prototype pollution in the MCP interpreter to bypass permission checks and take over owner accounts.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-5jr4-xmvf-frmj, GHSA-fm6v-qhr5-4c32

## What is CVE-2026-110842?

CVE-2026-110842 is a high-severity code injection vulnerability in n8n-io n8n, published on 14 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

n8n before 2.41.4 and 2.42.x before 2.42.1 contains a prototype pollution vulnerability in the MCP workflow-validation tool, whose interpreter evaluates caller-supplied code in the main process, reads inherited properties, and permits assignment onto shared prototypes. An authenticated member holding only a workflow:read grant can replace a built-in method with one returning a truthy value so server-side permission checks accept unheld scopes, enabling takeover of owner accounts not protected by MFA.

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

## Which versions are affected by CVE-2026-110842?


## How do I fix CVE-2026-110842?

No fix has been published for CVE-2026-110842 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-110842 being exploited?

There is no known exploitation of CVE-2026-110842 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110842 and fix it if it is affected.

What it is: CVE-2026-110842 is a high-severity code injection vulnerability in n8n-io n8n, published on 14 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-110842 in the wild and no public exploit code.

Affected product: n8n-io n8n. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-110842/ (Markdown: https://insights.sbomify.com/CVE-2026-110842/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110842
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110842
- OSV: https://osv.dev/vulnerability/CVE-2026-110842

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-110842/
Summaries are generated and may contain mistakes; the official description above is the record.