CVE-2026-42235 Details
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.
A cross-site scripting vulnerability has been identified in n8n, an open-source workflow automation platform, affecting versions prior to 1.123.32, 2.17.4, and 2.18.1. The issue arises when an unauthenticated attacker registers a malicious MCP OAuth client with a crafted client_name. If a victim user authorizes the OAuth consent dialog and a second user later revokes that access, a toast notification will display the injected script. Clicking the link executes arbitrary JavaScript in the victim's authenticated n8n browser session, potentially leading to theft of credentials and session tokens, manipulation of workflows, or privilege escalation.
Users should upgrade to n8n version 2.14.2 or later. If an immediate upgrade is not possible, access to the n8n instance and the MCP OAuth registration endpoint should be restricted to trusted users only. Additionally, the MCP server functionality can be disabled if not actively required.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 5, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/n8n-io/n8n/security/advisories/GHSA-537j-gqpc-p7fq | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
| CWE-87 | Improper Neutralization of Alternate XSS Syntax | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| n8n n8n | < 1.123.32 >= 2.17.0, < 2.17.4 2.18.0 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 6, 2026 | Initial Analysis | [email protected] |
| May 4, 2026 | New CVE Received | [email protected] |