CVE-2026-42226 Overview
CVE-2026-42226 is a missing authorization vulnerability [CWE-862] in n8n, an open source workflow automation platform. The dynamic-node-parameters endpoints fail to verify whether the authenticated caller is authorized to use a supplied credential reference. An authenticated user with access to a shared workflow can supply a foreign credential ID and a controlled destination URL, forcing the backend to authenticate against attacker-infrastructure using another user's credential. The flaw enables exfiltration of reusable API keys belonging to other tenants. Versions prior to 1.123.33 and 2.17.5 are affected. The issue is patched in 1.123.33, 2.17.5, and 2.18.0.
Critical Impact
Authenticated users can coerce the n8n backend to authenticate to attacker-controlled endpoints using credentials owned by other users, leaking reusable API keys across tenants.
Affected Products
- n8n versions prior to 1.123.33
- n8n versions 2.x prior to 2.17.5
- n8n Enterprise (Node.js) deployments using shared workflows
Discovery Timeline
- 2026-05-04 - CVE-2026-42226 published to NVD
- 2026-05-06 - Last updated in NVD database
Technical Details for CVE-2026-42226
Vulnerability Analysis
The vulnerability resides in n8n's dynamic-node-parameters endpoints, which resolve credentials at runtime to populate parameter options for nodes. These endpoints accept a credential identifier in the request body but do not enforce ownership or sharing checks against the authenticated caller. As a result, any logged-in user with access to a shared workflow can reference a credential ID belonging to another user.
The backend then decrypts the foreign credential and uses it inside a helper execution path. Critically, the same code path also lets the caller control the destination URL of the outbound request. The combination produces a server-side request forgery primitive that authenticates with someone else's secrets to an attacker-chosen endpoint.
Because many n8n credentials carry long-lived API keys or OAuth bearer tokens, the leaked material is replayable outside n8n. Any node type that resolves credentials through the affected endpoints is in scope, broadening the impact across integrations.
Root Cause
The root cause is missing authorization [CWE-862]. The endpoint validates authentication but skips the check that the caller is permitted to reference the supplied credentialId. Sharing scope and ownership constraints applied elsewhere in n8n are not enforced on this helper path.
Attack Vector
Exploitation requires network access to the n8n instance and a low-privileged authenticated account with access to at least one shared workflow. The attacker submits a crafted request to a dynamic-node-parameters endpoint specifying a foreign credentialId and an attacker-controlled URL. The backend decrypts the credential and issues an authenticated request to the attacker, exposing the secret in the Authorization header or query parameters.
No user interaction is required from the credential owner, and the attack is fully scriptable against multi-tenant n8n deployments.
Detection Methods for CVE-2026-42226
Indicators of Compromise
- Outbound HTTP requests from the n8n backend to unfamiliar external hosts originating from dynamic-node-parameters execution paths.
- Application logs showing credential resolution where the requesting user does not own or share the referenced credentialId.
- Spikes in calls to /rest/dynamic-node-parameters/* endpoints from a single authenticated session referencing many distinct credential IDs.
Detection Strategies
- Correlate n8n audit logs with egress proxy logs to identify backend requests targeting non-allowlisted destinations during dynamic parameter resolution.
- Alert on enumeration patterns where one user iterates through sequential or varied credentialId values in short time windows.
- Compare credential ownership metadata against the requester identity at the reverse proxy or WAF layer to flag mismatches.
Monitoring Recommendations
- Forward n8n application and access logs to a centralized SIEM and create rules for cross-tenant credential reference attempts.
- Monitor outbound DNS and HTTP traffic from the n8n host for connections to newly registered or low-reputation domains.
- Track failed and successful authentications on third-party APIs tied to n8n credentials for anomalous source IPs that indicate replay of leaked keys.
How to Mitigate CVE-2026-42226
Immediate Actions Required
- Upgrade n8n to version 1.123.33, 2.17.5, or 2.18.0 without delay.
- Rotate all credentials stored in n8n that may have been exposed through shared workflows, prioritizing long-lived API keys and OAuth refresh tokens.
- Review workflow sharing settings and revoke unnecessary access to limit which users can reach the affected endpoints.
Patch Information
The maintainers fixed the issue by enforcing authorization checks on the dynamic-node-parameters endpoints so that credential resolution validates the caller's right to use the supplied credential reference. Refer to the n8n GitHub Security Advisory GHSA-r4v6-9fqc-w5jr for upgrade guidance.
Workarounds
- Restrict workflow sharing to trusted users only until the upgrade is applied.
- Place an egress proxy in front of the n8n backend with an allowlist of approved destination hosts to blunt URL-controlled exfiltration.
- Audit existing workflows for unexpected nodes that perform outbound HTTP requests using shared credentials.
# Upgrade n8n via npm to a patched release
npm install -g n8n@2.18.0
# Or pull the patched Docker image
docker pull n8nio/n8n:2.18.0
docker stop n8n && docker rm n8n
docker run -d --name n8n -p 5678:5678 n8nio/n8n:2.18.0
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
