n8n: Member-Level Users Can Execute Other Users' MCP Server Trigger Workflows via Missing OAuth Authorization Check
Impact
The OAuth 2.1 consent and token-issuance flow introduced in n8n 2.27.0 does not verify that the authenticated user has access to the workflow referenced as the OAuth resource. A member-level user can register an OAuth client, self-approve consent for another user's n8n OAuth2-protected MCP Server Trigger workflow, and obtain a valid token for it.
The workflow runs in the owner's project context with the owner's stored credentials. The attacker sets the tool inputs and reads the outputs, which may include data from the owner's connected integrations, breaking user and project isolation. The resulting executions appear under the owner's account and are not visible to the attacker.
This issue only affects instances running n8n 2.27.0 or later where at least one active workflow uses an MCP Server Trigger node configured with n8n OAuth2 authentication.
Patches
The issue has been fixed in n8n versions 2.29.8 and 2.30.1. Users should upgrade to one of these versions 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.
- Audit active workflows using the MCP Server Trigger with
n8n OAuth2authentication and consider switching to a different authentication method or deactivating them until the patch is applied.
These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
Betroffene Software
Klicken Sie auf eine Technologie, um alle zugehörigen Schwachstellen anzuzeigen.
| Plattform | Paket | Anfällige Versionen | Behoben in |
|---|---|---|---|
| npm-Paket | n8n | >= 2.30.0, < 2.30.1, < 2.29.8 | 2.30.1, 2.29.8 |
Verweise
- https://github.com/n8n-io/n8n/security/advisories/GHSA-q5xf-xhwf-cwqf
- https://nvd.nist.gov/vuln/detail/CVE-2026-65594
- https://github.com/n8n-io/n8n
- https://github.com/n8n-io/n8n/releases/tag/n8n@2.29.8
- https://github.com/n8n-io/n8n/releases/tag/n8n@2.30.1
- https://www.vulncheck.com/advisories/n8n-before-missing-oauth-authorization-check
- CVSS-Vektor
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:H/SI:L/SA:N- Schwäche (CWE)
CWE-863- Plattform
- npm
- Paket
n8n- Veröffentlicht
- 22.07.2026
- Aktualisiert
- 11.10.2026 10:22
Quellen und Lizenzen
OSV / GitHub Advisory Database - GHSA-q5xf-xhwf-cwqf - CC BY 4.0
Schwachstellenhistorie: n8n
Alle veröffentlichten Schwachstellen dieses Pakets (npm-Paket), neueste zuerst. Zeigt, ob es ein einmaliger Ausrutscher ist oder ein Paket, das man im Auge behalten muss.
- Einträge insgesamt
- 156
- Erste → letzte
- 05.2023 09.2026
- Ohne Fix
- 1
- In Angriffen ausgenutzt
- 1
Verteilung nach Schweregrad
- Kritisch 24
- Hoch 58
- Mittel 74
Veröffentlichungen pro Jahr
- 2023: 3
- 2024: 0
- 2025: 14
- 2026: 139
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