CVE-2026-103254 Overview
CVE-2026-103254 is a path traversal vulnerability in n8n, the open-source workflow automation platform. The flaw exists in the signed resume URL generation logic used for Send-and-Wait approval gates. Attackers with workflow creation permissions can mint valid approval URLs for gates in projects they cannot access. The issue stems from unresolved traversal sequences in caller-controlled node identifiers, enabling cross-project approval forgery. The vulnerability affects n8n versions before 1.123.80, 2.0.0 through 2.39.5, and 2.40.0. It is classified under [CWE-22] (Improper Limitation of a Pathname to a Restricted Directory).
Critical Impact
An authenticated attacker can forge signed approval URLs for Send-and-Wait gates across project boundaries, breaking workflow authorization and integrity controls.
Affected Products
- n8n versions prior to 1.123.80
- n8n versions 2.0.0 through 2.39.5
- n8n version 2.40.0
Discovery Timeline
- 2026-10-01 - CVE-2026-103254 published to NVD
- 2026-10-06 - Last updated in NVD database
Technical Details for CVE-2026-103254
Vulnerability Analysis
n8n's Send-and-Wait node pauses workflow execution and emits a signed resume URL. Approvers click the URL to continue or reject execution. The signing routine binds the URL to a workflow execution and node identifier so that only legitimate approvers can resume the gate.
The vulnerability resides in how the resume URL generator handles node identifiers supplied by workflow authors. The signing path does not normalize or reject traversal sequences such as ../ in the node ID before incorporating it into the signed payload. An attacker with permission to create workflows in a project they control can embed crafted node IDs that, once resolved on the receiving side, point to gates in projects they are not authorized to reach.
Because the resulting URL carries a valid signature produced by the server itself, downstream validation accepts the forged approval and advances the targeted workflow. This breaks the per-project authorization boundary that n8n enforces elsewhere.
Root Cause
The root cause is missing path canonicalization on caller-controlled input prior to use in a security-sensitive signing operation. The server trusts the node ID string without resolving relative segments, so the signed artifact and the eventual resource lookup disagree on the target.
Attack Vector
Exploitation requires an authenticated account with workflow creation privileges. The attacker builds a workflow containing a node whose identifier includes traversal sequences, triggers signed resume URL generation, and submits the resulting URL to approve or reject a gate in another project. No user interaction from the victim project is required. Refer to the GitHub Security Advisory GHSA-597w-c3jh-g8fg and the VulnCheck Path Traversal Advisory for further technical context.
Detection Methods for CVE-2026-103254
Indicators of Compromise
- Workflow definitions containing node IDs with ../, ..\, URL-encoded (%2e%2e%2f), or double-encoded traversal sequences.
- Resume URL requests to /webhook-waiting/ or /rest/waiting-webhooks/ endpoints referencing execution IDs outside the caller's project scope.
- Audit log entries showing approvals completed by users who lack role bindings to the target workflow's project.
Detection Strategies
- Inspect workflow JSON on creation and update for node IDs that fail strict character allowlists (alphanumerics, hyphen, underscore).
- Correlate resume URL callbacks with the originating workflow owner and compare project membership of the approver.
- Alert on signed resume URLs whose decoded node ID path differs from its canonicalized form.
Monitoring Recommendations
- Enable verbose logging on the Send-and-Wait node and the webhook resume handlers.
- Export n8n audit events to a central log store and build detections for cross-project approval activity.
- Track workflow creation volume per user to surface accounts generating anomalous numbers of signed URLs.
How to Mitigate CVE-2026-103254
Immediate Actions Required
- Upgrade n8n to 1.123.80, 2.39.6, or 2.40.1 or later depending on the branch in use.
- Review all users with workflow creation permissions and revoke access for accounts that do not require it.
- Audit recent Send-and-Wait approvals for cross-project activity during the exposure window.
Patch Information
The maintainers released fixes in n8n 1.123.80, 2.39.6, and 2.40.1. The patches normalize node identifiers before they are included in signed resume URLs and reject identifiers containing traversal sequences. See the GitHub Security Advisory GHSA-597w-c3jh-g8fg for release notes and commit references.
Workarounds
- Restrict workflow authoring to trusted operators until the upgrade is complete.
- Place n8n behind an authenticating reverse proxy that validates project scope on resume URL callbacks.
- Disable or remove Send-and-Wait nodes from workflows in multi-tenant deployments where upgrade is not immediately feasible.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
