CVE-2026-54052: n8n-MCP: Cross-tenant access to workflow version backups in multi-tenant HTTP deployments

n8n-mcp keeps automatic backups of a workflow before each update, and exposes them through the n8n_workflow_versions tool. In HTTP mode with ENABLE_MULTI_TENANT=true, one server and one database serve several tenants, but this version store was not separated by tenant. Any authenticated tenant could therefore call the tool and read snapshots that belong to other tenants, or delete those tenants' stored backups.

A snapshot holds the full node definitions of a workflow. That can include credential references and authorization headers set on nodes, so the leak is a confidentiality problem as well as an integrity and availability one. An attacker needs a valid tenant login (PR:L) and network access to the HTTP endpoint. The CVSS scope is changed because one tenant reaches data of others.

The advisory scopes the risk to shared multi-tenant hosting. A single user running n8n-mcp over stdio with Claude Desktop, or one tenant per instance and database, has no other tenant to expose.

npm package n8n-mcp, version 2.56.0 and earlier, in HTTP mode with ENABLE_MULTI_TENANT=true. Not affected: stdio or single-user deployments, and single-tenant HTTP deployments with one tenant per instance and database. Check the version and the setting:

npm ls n8n-mcp
grep ENABLE_MULTI_TENANT .env

For Docker, check the image tag and the container environment.

Upgrade to n8n-mcp 2.56.1:

npm install [email protected]

The stored version history is now isolated per instance, so a tenant can only reach its own backups. The upgrade runs a one-time migration that isolates existing history and clears previously stored, un-scoped backups. Those are automatic, short-retention backups.

If you cannot upgrade yet, the advisory gives three workarounds:

• Set DISABLED_TOOLS=n8n_workflow_versions in the server environment. This closes the access path for all tenants. Automatic backups continue.
• Do not run multi-tenant. Give each tenant its own instance and database.
• Restrict network access to the HTTP endpoint to trusted operators.

The advisory lists no log indicators. Review HTTP access logs and tool-call logs for n8n_workflow_versions calls, especially from tenants that never update workflows, or listing and deletion calls that cover many workflows. Check for missing backups that tenants expected to find. Because snapshots may contain authorization headers and credential references, treat tokens on nodes in any multi-tenant 2.56.0 or earlier deployment as potentially exposed, and rotate them after upgrading.

Impact

In multi-tenant HTTP deployments — where a single n8n-mcp server serves several tenants — the locally stored workflow version history (the automatic backups taken before workflow updates) was not isolated per tenant. An authenticated tenant could read workflow version snapshots belonging to other tenants, and could delete or destroy other tenants' stored backups.

A stored snapshot includes full node definitions, so the exposed data can contain credential references and authorization headers configured on nodes. This is therefore a confidentiality issue in addition to an integrity/availability one.

Affected configurations

• HTTP mode with multi-tenancy enabled (ENABLE_MULTI_TENANT=true), where multiple tenants are served by a single shared instance and database.

Not affected:

• stdio / single-user deployments (e.g. Claude Desktop).
• Single-tenant HTTP deployments (one tenant per instance and database).

Affected versions

<= 2.56.0

Patched version

2.56.1. The stored version history is now isolated per instance, so a tenant can only access its own backups. Upgrading runs a one-time migration that isolates existing history and clears previously stored, un-scoped backups (these are auto-created, short-retention backups).

Workarounds

If users cannot upgrade immediately:

• Disable the workflow version tool by setting DISABLED_TOOLS=n8n_workflow_versions in the server environment (for example, in your Docker .env). This removes the affected tool from the deployment for all tenants; automatic backups are unaffected, but the cross-tenant access path is closed.
• Alternatively, do not run in multi-tenant mode — serve each tenant from a separate instance with its own database, so no local store is shared between tenants.
• Restrict network access to the HTTP endpoint to trusted operators.

stdio and single-tenant HTTP deployments are not affected.

Credit

Reported by Francisco Rosales (@0xmagic0) and coordinated by Ax Sharma (@axsharma) of Manifold Security.