# CVE-2026-42235: n8n: XSS via MCP OAuth client

> An unauthenticated attacker can inject JavaScript via a malicious MCP OAuth client name, leading to session hijacking and privilege escalation in n8n.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 4 May 2026
- **Updated:** 5 May 2026
- **Also known as:** GHSA-537j-gqpc-p7fq

## What is CVE-2026-42235?

CVE-2026-42235 is a high-severity cross-site scripting vulnerability in N8n N8n, published on 4 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, an unauthenticated attacker could register a malicious MCP OAuth client with a crafted client_name. If a victim user authorized the OAuth consent dialog and a second user subsequently revoked that access, a toast notification would render the injected script. Clicking the link would execute arbitrary JavaScript in the victim's authenticated n8n browser session, enabling credential and session token theft, workflow manipulation, or privilege escalation. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.

Weakness: CWE-87 (Improper Neutralization of Alternate XSS Syntax), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-42235?

6 open source packages ship an affected version, including n8n. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `n8n` | npm | All versions | 1.123.32 |
| `n8n` | npm | All versions | 1.123.32 |
| `n8n` | npm | From 2.17.0 | 2.17.4 |
| `n8n` | npm | From 2.17.0 | 2.17.4 |
| `n8n` | npm | From 2.18.0 | 2.18.1 |
| `n8n` | npm | From 2.18.0 | 2.18.1 |

Products: N8n N8n.

## How do I fix CVE-2026-42235?

Upgrade n8n to a fixed version for your release line: 1.123.32, 2.17.4 or 2.18.1.

## Is CVE-2026-42235 being exploited?

There is no known exploitation of CVE-2026-42235 in the wild and no public exploit code.

## Other vulnerabilities in N8n N8n

- [CVE-2025-68613](https://insights.sbomify.com/CVE-2025-68613/): n8n Improper Control of Dynamically-Managed Code Resources (critical 10.0, exploited in the wild)
- [CVE-2026-21877](https://insights.sbomify.com/CVE-2026-21877/): n8n is vulnerable to Remote Code Execution via Arbitrary File Write (critical 10.0)
- [CVE-2026-21858](https://insights.sbomify.com/CVE-2026-21858/): n8n Vulnerable to Unauthenticated File Access via Improper Webhook Request Handling (critical 10.0)
- [CVE-2026-1470](https://insights.sbomify.com/CVE-2026-1470/): n8n Unsafe Workflow Expression Evaluation Allows Remote Code Execution (critical 9.9)
- [CVE-2025-68668](https://insights.sbomify.com/CVE-2025-68668/): n8n Vulnerable to Arbitrary Command Execution in Pyodide based Python Code Node (critical 9.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42235 and fix it if it is affected.

What it is: CVE-2026-42235 is a high-severity cross-site scripting vulnerability in N8n N8n, published on 4 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-42235 in the wild and no public exploit code.

Affected packages and fixed versions:
- n8n (npm): affected all versions; fixed in 1.123.32
- n8n (npm): affected all versions; fixed in 1.123.32
- n8n (npm): affected from 2.17.0; fixed in 2.17.4
- n8n (npm): affected from 2.17.0; fixed in 2.17.4
- n8n (npm): affected from 2.18.0; fixed in 2.18.1
- n8n (npm): affected from 2.18.0; fixed in 2.18.1

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-2026-42235/ (Markdown: https://insights.sbomify.com/CVE-2026-42235/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42235
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42235
- OSV: https://osv.dev/vulnerability/CVE-2026-42235

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42235/
Summaries are generated and may contain mistakes; the official description above is the record.