CVE-2026-42235

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.

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.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2026-42235 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.123.32, 2.18.1, 2.17.4); upgrading removes the vulnerable code path.

Kodem intelligence

This issue has been fixed in n8n version 2.14.2. Users should upgrade to this version or later to remediate the vulnerability.

1. What is CVE-2026-42235? CVE-2026-42235 is a high-severity cross-site scripting (XSS) vulnerability in n8n (npm), affecting versions < 1.123.32. It is fixed in 1.123.32, 2.18.1, 2.17.4. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-42235? CVE-2026-42235 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of n8n are affected by CVE-2026-42235? n8n (npm) versions < 1.123.32 is affected.
4. Is there a fix for CVE-2026-42235? Yes. CVE-2026-42235 is fixed in 1.123.32, 2.18.1, 2.17.4. Upgrade to this version or later.
5. Is CVE-2026-42235 exploitable, and should I be worried? Whether CVE-2026-42235 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-42235 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-42235?
   • Upgrade n8n to 1.123.32 or later
   • Upgrade n8n to 2.18.1 or later
   • Upgrade n8n to 2.17.4 or later