n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions
n8n
- Severity
- Critical, CVSS 10.0
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L
- Record
- CVE-2026-54309
- Affects
- n8n
- Known exploited
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- June 23, 2026
- Source last modified
- October 26, 2026
Description
n8n is an open source workflow automation platform. Prior to 2.25.7 and 2.26.2, 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). This vulnerability is fixed in 2.25.7 and 2.26.2.
Description quoted from the NVD record.
Who is affected
This flaw affects n8n, a tool for connecting apps and automating routine tasks, in versions before 2.25.7 and 2.26.2. The problem is in the browser-control component (@n8n/mcp-browser), and only when it is run in its web connection mode. In that setup it accepts requests without any login, so anyone who can reach it over the network, or any website the user visits, can use its browser-control tools. Where the n8n AI Browser Bridge extension is installed and connected, an attacker could open web pages, run code, and read cookies and stored data in the user's real browser. This flaw is rated Critical.
What to do
- The person who installed or runs n8n for your organization should check whether the browser-control component (
@n8n/mcp-browser) is in use and whether it is run in its web connection mode, since only that setup is affected. - Update n8n to version
2.25.7or2.26.2, which fix this flaw. Doing this is worthwhile even if you are unsure how the component is set up. - If an IT provider or vendor runs n8n for your organization, send them this advisory and ask when the update will be done.
Analysis written from the source record as of October 26, 2026 and reviewed before publishing.