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CVE-2026-42235 — Vulnerability in n8n — CVE Details

HIGH

n8n Vulnerable to XSS via MCP OAuth client

Published April 29, 2026Updated May 8, 2026Source: osv

Summary

## Impact 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. ## Patches This issue has been fixed in n8n version 2.14.2. Users should upgrade to this version or later to remediate the vulnerability. ## Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - Restrict access to the n8n instance and the MCP OAuth registration endpoint to trusted users only. - Disable MCP server functionality if it is not actively required. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

Advisory Timeline

  • First published April 29, 2026 (166 days ago).
  • Last revised May 8, 2026 — 8 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

npm
Update n8n to 2.18.1 or later
npm install n8n@2.18.1
npm
Update n8n to 1.123.32 or later
npm install n8n@1.123.32
npm
Update n8n to 2.17.4 or later
npm install n8n@2.17.4

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (3)

Affects 1 ecosystem: npm (1).

PackageEcosystemAffectedFixed In
n8n
npm
All versions2.18.1
n8n
npm
All versions1.123.32
n8n
npm
All versions2.17.4

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.2 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:L

References

Frequently Asked Questions

What is CVE-2026-42235?
n8n Vulnerable to XSS via MCP OAuth client This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.2/10).
How do I check if my project is affected by CVE-2026-42235?
CVE-2026-42235 affects n8n. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-42235 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.2

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-537j-gqpc-p7fq

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