CVE-2026-55608
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.
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Exploitation outlook
- Low exploitation risk0.16% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 6% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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