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Medium

n8n: Member-Level Users Can Execute Other Users' MCP Server Trigger Workflows via Missing OAuth Authorization Check

  • Disclosed: 22.07.2026
  • Updated: 11.10.2026 10:22

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 OAuth2 authentication 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.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package n8n >= 2.30.0, < 2.30.1, < 2.29.8 2.30.1, 2.29.8

References

CVSS score -
CVSS vector
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
Weakness (CWE)
CWE-863
Platform
npm
Package
n8n
Disclosed
22.07.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-q5xf-xhwf-cwqf - CC BY 4.0

Vulnerability history: n8n

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (156) in the archive
Total entries
156
First → latest
05.2023 09.2026
Without a fix
1
Exploited in attacks
1

Severity breakdown

  • Critical 24
  • High 58
  • Medium 74

Disclosures per year

Severity:
  1. n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code Execution
    High CVE-2026-86083 < 1.123.76, >= 2.38.0, < 2.38.2, >= 2.0.0, < 2.37.7 1.123.76, 2.38.2, 2.37.7
  2. n8n: Domain-Restriction Bypass via Unguarded Model-Search Endpoint in OpenAI Chat Model Node
    High CVE-2026-86082 < 1.123.76, >= 2.38.0, < 2.38.2, >= 2.0.0, < 2.37.7 1.123.76, 2.38.2, 2.37.7
  3. n8n: Regular Expression Denial of Service in the Default Blocked-File-Pattern Match via a Git Node Clone Path
    High CVE-2026-86081 < 1.123.76, >= 2.38.0, < 2.38.2, >= 2.0.0, < 2.37.7 1.123.76, 2.38.2, 2.37.7
  4. n8n: Unauthenticated Persistent Storage Exhaustion via OAuth Dynamic Client Registration Endpoint
    High CVE-2026-86075 >= 2.38.0, < 2.38.2, < 2.37.7 2.38.2, 2.37.7
  5. n8n: Expression Sandbox Escape via Class-Field Sanitizer Rebinding Can Lead to Code Execution
    High CVE-2026-86076 < 1.123.76, >= 2.38.0, < 2.38.2, >= 2.0.0, < 2.37.7 1.123.76, 2.38.2, 2.37.7
  6. n8n: Member-Level Users Can Execute Other Users' MCP Server Trigger Workflows via Missing OAuth Authorization Check this entry
    Medium CVE-2026-65594 >= 2.30.0, < 2.30.1, < 2.29.8 2.30.1, 2.29.8
  7. n8n: Prototype Pollution via Dot-Notation Field Names Leads To Instance-Wide Denial of Service
    High CVE-2026-72749 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  8. n8n: Edit Image Node Format Injection Allows Arbitrary File Write
    High CVE-2026-72762 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  9. n8n: Shared-Workflow Editor Can Exfiltrate Credentials via Inline Sub-Workflow JSON
    High CVE-2026-72763 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  10. n8n: Credential Authorization Bypass via Expression in HTTP Request Node `genericAuthType`
    High CVE-2026-72774 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  11. n8n: Expression sandbox escape via arrow-function bodies enabling command execution
    High CVE-2026-72765 >= 2.32.0, < 2.32.1, < 2.31.5 2.32.1, 2.31.5
  12. n8n: Send Email Node Arbitrary File Read and SSRF via Nodemailer Content-Object Type Confusion
    High CVE-2026-72766 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  13. n8n: Authenticated code execution in the n8n Git node
    High CVE-2026-72767 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  14. n8n: Git Node fetch/pull/pushTags Operations Bypass Sandbox Path Restriction
    High CVE-2026-72770 < 1.123.67, >= 2.32.0, < 2.32.1, >= 2.0.0-rc.0, < 2.31.5 1.123.67, 2.32.1, 2.31.5
  15. n8n: Bypass "Allowed HTTP Request Domains" Credential Restriction in Multiple AI and LLM Nodes
    High CVE-2026-72771 >= 2.32.0, < 2.32.1, < 2.31.5 2.32.1, 2.31.5
  16. n8n: Account Takeover via Unverified Email Claim in Token Exchange Embed Login
    High CVE-2026-72772 >= 2.32.0, < 2.32.1, < 2.31.5 2.32.1, 2.31.5
  17. n8n: SSO Instance-Role Provisioning Allows Privilege Escalation to Instance Owner
    High CVE-2026-65016 < 1.123.64, >= 2.30.0, < 2.30.1, >= 2.0.0-rc.0, < 2.29.8 1.123.64, 2.30.1, 2.29.8
  18. n8n: Legacy Expression Evaluator Sanitizer Bypass Leads to Authenticated Code Execution
    High CVE-2026-65591 < 1.123.64, >= 2.30.0, < 2.30.1, >= 2.0.0-rc.0, < 2.29.8 1.123.64, 2.30.1, 2.29.8
  19. n8n: Privilege Escalation and Code Execution via Full Public API Key Scope Assignment to Token Exchange JWTs
    High CVE-2026-65595 >= 2.30.0, < 2.30.1, < 2.29.8 2.30.1, 2.29.8
  20. n8n: Cross-Issuer Token Exchange Account Binding via Subject-Only Identity Resolution
    High CVE-2026-59208 >= 2.28.0, < 2.28.1, < 2.27.4 2.28.1, 2.27.4
Show more (20) Showing 20 of 83

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