{"id":"GHSA-qrx8-25qr-5r7v","summary":"n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions","details":"## 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.","aliases":["CVE-2026-54309"],"modified":"2026-07-20T13:45:32.235949356Z","published":"2026-06-16T23:32:31Z","database_specific":{"cwe_ids":["CWE-306"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-06-16T23:32:31Z","nvd_published_at":"2026-06-23T16:17:01Z"},"references":[{"type":"WEB","url":"https://github.com/n8n-io/n8n/security/advisories/GHSA-qrx8-25qr-5r7v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54309"},{"type":"PACKAGE","url":"https://github.com/n8n-io/n8n"}],"affected":[{"package":{"name":"n8n","ecosystem":"npm","purl":"pkg:npm/n8n"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.26.0"},{"fixed":"2.26.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-qrx8-25qr-5r7v/GHSA-qrx8-25qr-5r7v.json"}},{"package":{"name":"n8n","ecosystem":"npm","purl":"pkg:npm/n8n"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.25.7"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-qrx8-25qr-5r7v/GHSA-qrx8-25qr-5r7v.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N"}]}