{"id":"CVE-2026-54309","title":"n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions","summary":"n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions","severity":"high","cvss":10,"cwe":["CWE-306"],"vendor":"n8n","product":"n8n","ecosystem":"npm","affected":["n8n >= 2.26.0, < 2.26.2","n8n < 2.25.7"],"patched":["n8n 2.26.2","n8n 2.25.7"],"published":"2026-06-16","updated":"2026-06-16","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-qrx8-25qr-5r7v","references":[{"url":"https://github.com/n8n-io/n8n/security/advisories/GHSA-qrx8-25qr-5r7v"},{"url":"https://github.com/advisories/GHSA-qrx8-25qr-5r7v"}],"tags":["ghsa","npm"],"epss":0.00546,"epssPercentile":0.44425,"ingestedAt":"2026-06-29T14:31:47.469Z","slug":"CVE-2026-54309","body":"## Overview\n\n## Impact\nWhen `@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.\n\nWhere 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.\n\nThis 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.\n\n## Patches\nThe 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.\n\n## Workarounds\nIf upgrading is not immediately possible, administrators should consider the following temporary mitigations:\n- Avoid running `@n8n/mcp-browser` with the HTTP transport; use the default stdio transport instead.\n- If HTTP transport is required, restrict network access to the listening port to trusted clients only using host-based firewall rules.\n\nThese workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.\n\n## Affected packages\n\n- `n8n >= 2.26.0, < 2.26.2`\n- `n8n < 2.25.7`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `n8n 2.26.2`\n- `n8n 2.25.7`","depth":"twilight","depthScore":55,"depthScoreParts":{"impact":55,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}