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n8n-MCP: Incorrect authorization can expose default-scope workflow version backups in multi-tenant HTTP mode

Moderate severity GitHub Reviewed Published Jun 14, 2026 in czlonkowski/n8n-mcp • Updated Jul 14, 2026

Package

npm n8n-mcp (npm)

Affected versions

<= 2.57.3

Patched versions

2.57.4

Description

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.

References

@czlonkowski czlonkowski published to czlonkowski/n8n-mcp Jun 14, 2026
Published to the GitHub Advisory Database Jul 14, 2026
Reviewed Jul 14, 2026
Last updated Jul 14, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(20th percentile)

Weaknesses

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. Learn more on MITRE.

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. Learn more on MITRE.

CVE ID

CVE-2026-55608

GHSA ID

GHSA-2cf7-hpwf-47h9

Source code

Credits

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