CVE-2026-54309: n8n MCP Browser HTTP Transport Exposes Vulnerability

HIGH
Advisory Identifier: GHSA-qrx8-25qr-5r7v
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CVSS 10.0
CWE-306
Published
Advisory Summary

CVE-2026-54309 is a HIGH (CVSS 10.0) mcp browser http transport exposes vulnerability (CWE-306: Missing Authentication for Critical Function) affecting n8n libraries in the npm ecosystem. The issue involves mcp browser http transport exposes unauthenticated browser-control sessions. Remediation is available by upgrading affected packages to version 2.26.2, 2.25.7.

CVE-2026-54309 at a Glance

CVE Identifier CVE-2026-54309
GHSA Identifier GHSA-qrx8-25qr-5r7v
Severity HIGH
CVSS v3.1 Base Score 10.0
CWE Classification CWE-306: Missing Authentication for Critical Function
Affected Product n8n
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 10.0

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-54309

To remediate this vulnerability, upgrade all affected n8n dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

n8n fixed: 2.26.2 
npm install n8n@2.26.2
n8n fixed: 2.25.7 
npm install n8n@2.25.7
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls n8n

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-54309, inspect your project dependencies using npm:

npm ls n8n

Analyze the terminal output to locate any version of n8n in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.26.2), your application is affected.

Note: The npm ls n8n command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-306: Missing Authentication for Critical Function, where the product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. In n8n, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## 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.

CVE-2026-54309 Affected n8n Versions

2 component(s)
Fixed Versions:
2.26.22.25.7
Product / Package Ecosystem Affected Versions Fixed Version
n8n
npm/n8n
npm
≥ 2.26.0
< 2.26.2
2.26.2
n8n
npm/n8n
npm
< 2.25.7
2.25.7

References

GitHub Advisory / Wiki ADVISORY
https://github.com/n8n-io/n8n/security/advisories/GHSA-qrx8-25qr-5r7v
NVD — CVE-2026-54309 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54309
n8n Source Repository REPOSITORY
https://github.com/n8n-io/n8n

Frequently Asked Questions

What is CVE-2026-54309?
CVE-2026-54309 is a security vulnerability in n8n involving MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions under CWE-306: Missing Authentication for Critical Function.
Which n8n versions are affected?
Affected versions include releases prior to 2.26.2, 2.25.7 across affected packages: n8n.
What version fixes CVE-2026-54309?
Upgrading to 2.26.2, 2.25.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is n8n affected?
Yes, n8n is affected in releases prior to 2.26.2, 2.25.7. Upgrade your dependency to 2.26.2, 2.25.7 or later.
What is the CVSS score of CVE-2026-54309?
CVE-2026-54309 has a CVSS v3.1 base score of 10.0 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L.
What CWE is associated with CVE-2026-54309?
CVE-2026-54309 is classified under CWE-306: Missing Authentication for Critical Function (The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.).
How can I check npm dependencies for CVE-2026-54309?
Run the dependency tree command: 'npm ls n8n'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qrx8-25qr-5r7v",
  "modified" : "2026-07-20T13:39:49Z",
  "published" : "2026-06-16T23:32:31Z",
  "aliases" : [ "CVE-2026-54309" ],
  "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.",
  "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.26.0"
      }, {
        "fixed" : "2.26.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.25.7"
      } ]
    } ]
  } ],
  "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"
  } ],
  "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"
  }
}