n8nGHSA-cw9w-vv67-hf73

n8n: Per-Resource OAuth Consent Bypass via Unbound Refresh Token Resource Substitution

MediumCVE-2026-86073 · Published Sep 10, 2026

Affected versions

Package	Affected	Fixed in
n8n npm	>= 2.38.0, < 2.38.1	2.38.1
	< 2.37.7	2.37.7

Details and references

## 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.

CVSS 4.0: 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
Severity from: GitHub (reviewed advisory)
Weakness: CWE-863
Also known as: CVE-2026-86073

More n8n advisories

All n8n

Date	Advisory	Severity	Fixed in
Sep 10	n8n: Expression Sandbox Escape via Class-Field Sanitizer Rebinding Can Lead to Code Execution CVE-2026-86076Highfixed in 1.123.76, 2.37.7, 2.38.2	High	1.123.76, 2.37.7, 2.38.2
Sep 10	n8n: Unauthenticated Persistent Storage Exhaustion via OAuth Dynamic Client Registration Endpoint CVE-2026-86075Highfixed in 2.37.7, 2.38.2	High	2.37.7, 2.38.2
Sep 10	n8n: Regular Expression Denial of Service in the Default Blocked-File-Pattern Match via a Git Node Clone Path CVE-2026-86081Highfixed in 1.123.76, 2.37.7, 2.38.2	High	1.123.76, 2.37.7, 2.38.2
Sep 10	n8n: Domain-Restriction Bypass via Unguarded Model-Search Endpoint in OpenAI Chat Model Node CVE-2026-86082Highfixed in 1.123.76, 2.37.7, 2.38.2	High	1.123.76, 2.37.7, 2.38.2
Sep 10	n8n: Anonymous Approval-Gate Bypass via Reused resumeToken over the Chat WebSocket CVE-2026-86077Mediumfixed in 2.37.7, 2.38.2	Medium	2.37.7, 2.38.2
Sep 10	n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code Execution CVE-2026-86083Highfixed in 1.123.76, 2.37.7, 2.38.2	High	1.123.76, 2.37.7, 2.38.2

Affected versions

More n8n advisories

Critical advisories by email