{"id":"GHSA-wg4g-395p-mqv3","summary":"n8n-MCP: Sensitive MCP tool-call arguments logged on authenticated requests in HTTP mode","details":"### Impact\n\nWhen `n8n-mcp` runs in HTTP transport mode, authenticated MCP `tools/call` requests had their full arguments and JSON-RPC params written to server logs by the request dispatcher and several sibling code paths before any redaction. When a tool call carries credential material — most notably `n8n_manage_credentials.data` — the raw values can be persisted in logs.\n\nIn deployments where logs are collected, forwarded to external systems, or viewable outside the request trust boundary (shared log storage, SIEM pipelines, support/ops access), this can result in disclosure of:\n\n- bearer tokens and OAuth credentials sent through `n8n_manage_credentials`\n- per-tenant API keys and webhook auth headers embedded in tool arguments\n- arbitrary secret-bearing payloads passed to any MCP tool\n\nThe issue requires authentication (`AUTH_TOKEN` accepted by the server), so unauthenticated callers cannot trigger it; the runtime exposure is also reduced by an existing console-silencing layer in HTTP mode, but that layer is fragile and the values are still constructed and passed into the logger. The fix removes the leak at the source.\n\nImpact category: **CWE-532** (Insertion of Sensitive Information into Log File). CVSS 3.1 score: **4.3 Medium** (`AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`).\n\n### Affected\n\nDeployments running n8n-mcp **v2.47.12 or earlier** in HTTP transport mode (`MCP_MODE=http`). The stdio transport short-circuits the relevant log calls and is not affected in practice.\n\n### Patched\n\n**v2.47.13** and later.\n\n- npm: `npx n8n-mcp@latest` (or pin to `\u003e= 2.47.13`)\n- Docker: `docker pull ghcr.io/czlonkowski/n8n-mcp:latest`\n\nThe patch routes tool-call arguments through a metadata-only summarizer (`summarizeToolCallArgs`) that records type, top-level key names, and approximate size — never values. The same pattern was adopted earlier for HTTP request bodies in GHSA-pfm2-2mhg-8wpx.\n\n### Workarounds\n\nIf developers cannot upgrade immediately:\n\n- Restrict access to the HTTP port (firewall, reverse proxy, or VPN) so only trusted clients can authenticate.\n- Restrict access to server logs (no shared SIEM ingestion, no support read-only access) until the upgrade lands.\n- Switch to stdio transport (`MCP_MODE=stdio`, the default for CLI invocation), which has no HTTP surface and short-circuits the affected log calls.\n\n### Credit\n\nn8n-MCP thanks [@Mirr2](https://github.com/Mirr2) (Organization / Jormungandr) for reporting this issue.","aliases":["CVE-2026-42282"],"modified":"2026-05-13T13:54:48.095286Z","published":"2026-04-25T23:35:28Z","database_specific":{"cwe_ids":["CWE-532"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-04-25T23:35:28Z","nvd_published_at":"2026-05-08T20:16:31Z"},"references":[{"type":"WEB","url":"https://github.com/czlonkowski/n8n-mcp/security/advisories/GHSA-wg4g-395p-mqv3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42282"},{"type":"WEB","url":"https://github.com/czlonkowski/n8n-mcp/commit/59b665bda36797823df238aeaf20adb862c9f451"},{"type":"PACKAGE","url":"https://github.com/czlonkowski/n8n-mcp"},{"type":"WEB","url":"https://github.com/czlonkowski/n8n-mcp/releases/tag/v2.47.13"}],"affected":[{"package":{"name":"n8n-mcp","ecosystem":"npm","purl":"pkg:npm/n8n-mcp"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.47.13"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-wg4g-395p-mqv3/GHSA-wg4g-395p-mqv3.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"}]}