n8n-MCP: Multi-tenant MCP requests fall back to process-level n8n credentials when tenant headers are absent or incomplete

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Summary

CVECVE-2026-45707
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-29 14:16:31 UTC
Updated2026-05-29 14:16:31 UTC
Descriptionn8n-MCP is an MCP server that provides AI assistants access to n8n node documentation, properties, and operations. Prior to 2.51.2, when ENABLE_MULTI_TENANT=true, the HTTP transport documents that the target n8n instance is selected per-request from x-n8n-url / x-n8n-key headers. Requests that omitted those headers — or supplied only one of them — silently fell back to the process-level N8N_API_URL / N8N_API_KEY credentials configured for the operator's own n8n instance. As a result, an authenticated MCP tenant could cause n8n management calls to execute against the operator's instance instead of its own. This affects HTTP-mode deployments of n8n-mcp that are run as a shared multi-tenant service. Single-tenant deployments (ENABLE_MULTI_TENANT unset or false) are not affected. This vulnerability is fixed in 2.51.2.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Problem Types: CWE-284 | CWE-284 CWE-284: Improper Access Control

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Czlonkowski N8n-mcp affected < 2.51.2 Not specified

References

ReferenceSourceLinkTags
github.com/czlonkowski/n8n-mcp/commit/853015d0897be7cf2d9d4726de195c938e... [email protected] github.com
github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-jxx9-px88-pj69 [email protected] github.com
github.com/czlonkowski/n8n-mcp/releases/tag/v2.51.2 [email protected] github.com
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