CVE-2026-55608: n8n-MCP Incorrect Authorization Can Expose Default-scope Vulnerability

MODERATE
Advisory Identifier: GHSA-2cf7-hpwf-47h9
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CVSS 4.2
CWE-200 CWE-863
Published
Advisory Summary

CVE-2026-55608 is a MODERATE (CVSS 4.2) incorrect authorization can expose default-scope vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting n8n-MCP libraries in the npm ecosystem. The issue involves incorrect authorization can expose default-scope workflow version backups in multi-tenant http mode. Remediation is available by upgrading affected packages to version 2.57.4.

CVE-2026-55608 at a Glance

CVE Identifier CVE-2026-55608
GHSA Identifier GHSA-2cf7-hpwf-47h9
Severity MODERATE
CVSS v3.1 Base Score 4.2
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product n8n-MCP
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 4.2

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

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

How to Fix CVE-2026-55608

To remediate this vulnerability, upgrade all affected n8n-MCP 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-mcp fixed: 2.57.4 
npm install n8n-mcp@2.57.4
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-mcp

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-55608, inspect your project dependencies using npm:

npm ls n8n-mcp

Analyze the terminal output to locate any version of n8n-MCP in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.57.4), your application is affected.

Note: The npm ls n8n-mcp 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-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In n8n-MCP, 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

## Summary In multi-tenant HTTP mode (`ENABLE_MULTI_TENANT=true`), an authenticated tenant could, under certain conditions, reach n8n-mcp's local default-scope `workflow_versions` backups instead of being confined to its own tenant scope. This affects n8n-mcp's own local workflow-version storage, not a normal n8n API capability. ## Impact An authenticated MCP HTTP tenant could read or delete workflow-version backups stored in the default (single-tenant) scope — for example backups left from a prior single-tenant deployment or a migration period. Workflow snapshots may contain sensitive workflow configuration depending on their contents. Single-tenant and stdio deployments are not affected. ## Affected versions `<= 2.57.3` ## Patched version `2.57.4` ## Remediation Upgrade to n8n-mcp `2.57.4` or later. The fix requires a complete tenant context in multi-tenant mode and fails closed for workflow-version access that cannot be attributed to a specific tenant. ## Workarounds - Restrict network access to the HTTP endpoint (firewall / reverse proxy / VPN) so only trusted callers can reach it. - Run in stdio mode, which has no multi-tenant HTTP surface. - If default-scope backups from a prior single-tenant deployment are not needed, removing them eliminates the exposure. ## Credit Reported by @DavidCarliez.

CVE-2026-55608 Affected n8n-MCP Versions

1 component(s)
Fixed Versions:
2.57.4
Product / Package Ecosystem Affected Versions Fixed Version
n8n-mcp
npm/n8n-mcp
npm
< 2.57.4
2.57.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-2cf7-hpwf-47h9
Security Fix Commit FIX COMMIT
https://github.com/czlonkowski/n8n-mcp/commit/c1ca1e73697feaec5ec2a5fb7e6992a2892b62c9
n8n-MCP Source Repository REPOSITORY
https://github.com/czlonkowski/n8n-mcp
n8n-MCP Release RELEASE
https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.57.4

Frequently Asked Questions

What is CVE-2026-55608?
CVE-2026-55608 is a security vulnerability in n8n-MCP involving Incorrect authorization can expose default-scope workflow version backups in multi-tenant HTTP mode under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which n8n-MCP versions are affected?
Affected versions include releases prior to 2.57.4 across affected packages: n8n-mcp.
What version fixes CVE-2026-55608?
Upgrading to 2.57.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is n8n-mcp affected?
Yes, n8n-mcp is affected in releases prior to 2.57.4. Upgrade your dependency to 2.57.4 or later.
What is the CVSS score of CVE-2026-55608?
CVE-2026-55608 has a CVSS v3.1 base score of 4.2 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-55608?
CVE-2026-55608 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check npm dependencies for CVE-2026-55608?
Run the dependency tree command: 'npm ls n8n-mcp'. 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-2cf7-hpwf-47h9",
  "modified" : "2026-07-14T20:26:39Z",
  "published" : "2026-07-14T20:26:39Z",
  "aliases" : [ "CVE-2026-55608" ],
  "summary" : "n8n-MCP: Incorrect authorization can expose default-scope workflow version backups in multi-tenant HTTP mode",
  "details" : "## Summary\n\nIn multi-tenant HTTP mode (`ENABLE_MULTI_TENANT=true`), an authenticated tenant could, under certain conditions, reach n8n-mcp's local default-scope `workflow_versions` backups instead of being confined to its own tenant scope. This affects n8n-mcp's own local workflow-version storage, not a normal n8n API capability.\n\n## Impact\n\nAn authenticated MCP HTTP tenant could read or delete workflow-version backups stored in the default (single-tenant) scope — for example backups left from a prior single-tenant deployment or a migration period. Workflow snapshots may contain sensitive workflow configuration depending on their contents. Single-tenant and stdio deployments are not affected.\n\n## Affected versions\n\n`<= 2.57.3`\n\n## Patched version\n\n`2.57.4`\n\n## Remediation\n\nUpgrade to n8n-mcp `2.57.4` or later. The fix requires a complete tenant context in multi-tenant mode and fails closed for workflow-version access that cannot be attributed to a specific tenant.\n\n## Workarounds\n\n- Restrict network access to the HTTP endpoint (firewall / reverse proxy / VPN) so only trusted callers can reach it.\n- Run in stdio mode, which has no multi-tenant HTTP surface.\n- If default-scope backups from a prior single-tenant deployment are not needed, removing them eliminates the exposure.\n\n## Credit\n\nReported by @DavidCarliez.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n-mcp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.57.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.57.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-2cf7-hpwf-47h9"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/czlonkowski/n8n-mcp/commit/c1ca1e73697feaec5ec2a5fb7e6992a2892b62c9"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/czlonkowski/n8n-mcp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.57.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-863" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-14T20:26:39Z",
    "nvd_published_at" : null
  }
}