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n8n-mcp affected by path traversal, redirect-following SSRF, and telemetry payload exposure

High severity GitHub Reviewed Published May 4, 2026 in czlonkowski/n8n-mcp • Updated May 8, 2026

Package

npm n8n-mcp (npm)

Affected versions

< 2.50.1

Patched versions

2.50.1

Description

Impact

n8n-mcp versions before 2.50.1 contained three independently-reported issues affecting deployments that run the n8n API integration:

  1. Caller-supplied identifiers were not validated before being used as URL path segments by the n8n API client. An authenticated MCP caller passing a crafted workflow id could cause outbound requests carrying the configured n8n API key to land on other same-origin endpoints, bypassing handler-level access controls (including DISABLED_TOOLS).

  2. Validated webhook, form, and chat trigger URLs followed redirects. A URL that passed initial validation could redirect the outbound request to a host that would otherwise have been rejected, with the response body returned to the caller. Reachable as non-blind SSRF over authenticated MCP calls.

  3. Mutation telemetry stored unredacted operation payloads. On instances running with the default opt-in telemetry, partial-update operation diffs were uploaded without redaction. Operation values can carry the same node-parameter values the workflow contains, including bearer tokens, API keys, and webhook secrets.

Severity

CVSS 8.3 (HIGH). Exploitation requires an authenticated MCP caller and an n8n API integration configured with an n8n API key.

Patched versions

Upgrade to n8n-mcp >= 2.50.1.

Workarounds

  • For issues (1) and (2): restrict network access to the HTTP transport (firewall, reverse-proxy ACL, or VPN) so only trusted callers can reach the MCP HTTP port; or switch to stdio mode, which exposes no HTTP surface for these issues.
  • For issue (3): set N8N_MCP_TELEMETRY_DISABLED=true in the environment before starting the server, or run npx n8n-mcp telemetry disable once.

Credit

Reported by @cybercraftsolutionsllc.

References

@czlonkowski czlonkowski published to czlonkowski/n8n-mcp May 4, 2026
Published to the GitHub Advisory Database May 8, 2026
Reviewed May 8, 2026
Last updated May 8, 2026

Severity

High

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
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low

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:L/PR:L/UI:N/S:U/C:H/I:H/A:L

EPSS score

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

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.

Server-Side Request Forgery (SSRF)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-8g7g-hmwm-6rv2

Source code

Credits

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