CVE-2026-54309

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

• Avoid running @n8n/mcp-browser with the HTTP transport; use the default stdio transport instead.
• If HTTP transport is required, restrict network access to the listening port to trusted clients only using host-based firewall rules.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

When @n8n/mcp-browser is run in HTTP transport mode, the MCP endpoint accepts session initialization and tool invocation requests without any authentication. Any network-reachable client, or any website visited by the user, can establish an MCP session and invoke browser-control tools.

Where the n8n AI Browser Bridge extension is installed and a browser connection is active, an unauthenticated caller can access browser-control capabilities including navigation, JavaScript evaluation, and cookie and storage access against the user's real browser profile.

This issue only affects instances where @n8n/mcp-browser is run with the HTTP transport (--transport http). The default transport is stdio, which is not affected.

A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.

CVE-2026-54309 has a CVSS score of 10.0 (High). The vector is network-reachable, no privileges required, and no user interaction. 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 (2.26.2, 2.25.7); upgrading removes the vulnerable code path.

Kodem intelligence

The issue has been fixed in n8n versions 2.25.7, and 2.26.2. Users should upgrade to one of these versions or later to remediate the vulnerability.

1. What is CVE-2026-54309? CVE-2026-54309 is a high-severity missing authentication for critical function vulnerability in n8n (npm), affecting versions >= 2.26.0, < 2.26.2. It is fixed in 2.26.2, 2.25.7. A critical operation is accessible without requiring any authentication.
2. How severe is CVE-2026-54309? CVE-2026-54309 has a CVSS score of 10.0 (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-2026-54309? n8n (npm) versions >= 2.26.0, < 2.26.2 is affected.
4. Is there a fix for CVE-2026-54309? Yes. CVE-2026-54309 is fixed in 2.26.2, 2.25.7. Upgrade to this version or later.
5. Is CVE-2026-54309 exploitable, and should I be worried? Whether CVE-2026-54309 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-2026-54309 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-2026-54309?
   • Upgrade n8n to 2.26.2 or later
   • Upgrade n8n to 2.25.7 or later