CVE-2026-103249 Overview
CVE-2026-103249 is a stored Document Object Model (DOM) cross-site scripting vulnerability in n8n, the workflow automation platform. The flaw resides in the Resource Locator parameter dropdown link handling. Workflow authors can inject malicious script URLs that execute arbitrary JavaScript in the editor origin. The payload triggers when another user opens the node dropdown and clicks the external-link icon. Malicious scripts persist across workflow imports and shares, enabling attacker code to spread between n8n instances. The vulnerability is tracked under [CWE-79] and affects n8n versions before 1.123.80, from 2.0.0 before 2.39.6, and from 2.40.0 before 2.40.1.
Critical Impact
Attackers with workflow authoring access can execute arbitrary JavaScript in the n8n editor origin of other users, enabling session theft, credential exposure, and workflow tampering.
Affected Products
- n8n versions before 1.123.80
- n8n versions 2.0.0 through 2.39.5
- n8n version 2.40.0
Discovery Timeline
- 2026-10-01 - CVE-2026-103249 published to the National Vulnerability Database
- 2026-10-01 - Last updated in NVD database
Technical Details for CVE-2026-103249
Vulnerability Analysis
The vulnerability is a stored DOM-based XSS in the Resource Locator parameter of n8n nodes. The Resource Locator is a user interface component that lets workflow authors reference external resources through a dropdown with associated links. When n8n renders the external-link icon in that dropdown, it accepts URL values supplied by the workflow author without sufficient sanitization. An attacker who can author a workflow can set the resource link to a javascript: URL. When a victim user opens the node dropdown in the editor and clicks the external-link icon, the browser executes the attacker-controlled script in the n8n editor origin.
Because the payload lives inside the workflow definition, it persists through exports, imports, and shared template distribution. A single malicious workflow template can therefore compromise every editor user who opens the node and interacts with the link control.
Root Cause
The root cause is improper neutralization of input used to construct an HTML anchor target in the Resource Locator dropdown. The link handler does not restrict URL schemes to safe values such as http, https, or mailto, permitting dangerous schemes like javascript: to pass through to the DOM.
Attack Vector
Exploitation requires low privileges (an authenticated workflow author) and user interaction. The attacker crafts a workflow where a Resource Locator parameter references a malicious URL. The attacker then shares, imports, or publishes the workflow. The victim opens the workflow in the editor, expands the node dropdown, and clicks the external-link icon. The injected script runs with the privileges of the victim session in the editor origin.
See the GitHub Security Advisory GHSA-c2wp-6fgc-xjq4 and the VulnCheck advisory on n8n XSS for additional technical context.
Detection Methods for CVE-2026-103249
Indicators of Compromise
- Workflow JSON definitions containing Resource Locator parameter values that begin with javascript:, data:, or other non-HTTP(S) URL schemes.
- Unexpected outbound requests from editor browser sessions to attacker-controlled domains following interaction with node dropdowns.
- Shared or imported workflow templates sourced from untrusted authors or public repositories.
Detection Strategies
- Scan workflow export files and database records for Resource Locator parameters whose link values do not match an allowlist of safe URL schemes.
- Review n8n audit logs for workflow creation or update events from accounts with limited reason to add external links.
- Instrument the editor origin with a Content Security Policy report endpoint to surface blocked inline script executions.
Monitoring Recommendations
- Monitor n8n application logs for workflow import events, particularly from new or low-reputation user accounts.
- Alert on anomalous browser session activity originating from the n8n editor domain, including credential or token access patterns.
- Track installed n8n versions across the environment and flag any instance running a version listed as affected.
How to Mitigate CVE-2026-103249
Immediate Actions Required
- Upgrade n8n to version 1.123.80, 2.39.6, or 2.40.1 or later, depending on the deployed release branch.
- Audit existing workflows for Resource Locator parameters containing non-HTTP(S) URL schemes and remove or sanitize them.
- Restrict workflow authoring and import permissions to trusted users until patching completes.
Patch Information
n8n maintainers have released fixed versions 1.123.80, 2.39.6, and 2.40.1. Operators should consult the GitHub Security Advisory GHSA-c2wp-6fgc-xjq4 for upgrade guidance and release notes.
Workarounds
- Disable or restrict import of workflow templates from untrusted sources until the upgrade is applied.
- Enforce a strict Content Security Policy on the n8n editor origin that disallows inline script execution and javascript: URL navigation.
- Require code review of shared workflow JSON before importing into production n8n instances.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
