n8n: Per-Resource OAuth Consent Bypass via Unbound Refresh Token Resource Substitution
Impact
The OAuth token endpoint bound an authorization code's first access token to the consented resource, but not its refresh token. Refreshing only checked that the requested resource was registered, not that it matched the original grant. An OAuth client approved for one workflow could refresh with a different workflow's URL and get a valid, unapproved token for it. The patch binds refresh tokens to the granted resource and rejects mismatches.
Exploitation requires the attacker to register an OAuth client, convince an authenticated user to approve that client for one known protected resource, and know the URL of a second protected resource that the consenting user is permitted to execute.
Patches
The issue has been fixed in n8n versions 2.38.1 and 2.37.7. Users should upgrade to this version or later to remediate the vulnerability.
Workarounds
If upgrading is not immediately possible, administrators should consider the following temporary mitigations:
- Restrict n8n instance access to fully trusted users only.
- Deactivate MCP Trigger, form, and webhook workflows that are protected by the n8n OAuth server if they are not required.
- Audit connected OAuth clients and revoke any that are not recognized or no longer needed.
- Require re-authorization for all existing OAuth clients after upgrading, as previously issued refresh tokens did not store the original resource binding.
These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de npm | n8n | >= 2.38.0, < 2.38.1, < 2.37.7 | 2.38.1, 2.37.7 |
Referencias
- https://github.com/n8n-io/n8n/security/advisories/GHSA-cw9w-vv67-hf73
- https://nvd.nist.gov/vuln/detail/CVE-2026-86073
- https://github.com/n8n-io/n8n/pull/37122
- https://github.com/n8n-io/n8n/pull/37588
- https://github.com/n8n-io/n8n/commit/18458482861097a26f874f30ad7e8136e268475c
- https://github.com/n8n-io/n8n/commit/380788fd9a3264c83161e868026a98731d274d88
- https://github.com/n8n-io/n8n
- https://github.com/n8n-io/n8n/releases/tag/n8n@2.37.7
- https://github.com/n8n-io/n8n/releases/tag/n8n@2.38.1
- Vector CVSS
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N- Debilidad (CWE)
CWE-863- Plataforma
- npm
- Paquete
n8n- Publicada
- 10.09.2026
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-cw9w-vv67-hf73 - CC BY 4.0
Historial de vulnerabilidades: n8n
Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 156
- Primera → última
- 05.2023 09.2026
- Sin corrección
- 1
- Explotada en ataques
- 1
Distribución por gravedad
- Crítica 24
- Alta 58
- Media 74
Divulgaciones por año
- 2023: 3
- 2024: 0
- 2025: 14
- 2026: 139
-
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