GHSA-qrx8-25qr-5r7v
n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
## Impact
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.
## Patches
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.
## 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.
References
External links from the advisory. They lead to third-party sites.