Summary
n8n contains a stored DOM cross-site scripting vulnerability in Resource Locator parameter dropdown link handling. A workflow author can store a malicious script URL that may execute JavaScript in the editor origin when another user opens the dropdown and selects its external-link icon.
Affected context
The vulnerability occurs in n8n workflows that use Resource Locator parameters with dropdown links rendered in the editor. Risk exists when workflow content containing attacker-controlled link values is imported, shared, or opened by another user, and the user interacts with the affected external-link control.
Exploit preconditions
- Attack surface: n8n workflow editor and Resource Locator parameter dropdown UI
- Required access: Ability to create, modify, import, or share workflow content
- Trigger point: Another user opens the affected node dropdown and clicks the external-link icon
- Persistence condition: The malicious link value remains stored in the workflow and survives imports or sharing
- Why exploitation is possible: The editor processes attacker-controlled URL data in a DOM context without adequately preventing script-capable schemes or unsafe navigation behavior
Why this happens
The underlying bug is insufficient validation and safe handling of user-controlled URLs rendered by the Resource Locator dropdown. A script-capable URL can persist in workflow data and reach a browser interaction path that evaluates or executes it in the n8n editor origin. This behavior maps to CWE-79: Improper Neutralization of Input During Web Page Generation, specifically stored DOM-based cross-site scripting.
Potential impact
- An attacker-controlled script may execute in the victim's n8n editor context
- The script could read or alter accessible workflow and application data
- An attacker could perform actions available to the affected user's editor session
- Sensitive information displayed in the editor could be exposed
- Shared or imported workflows could enable repeated exposure across users
General mitigation guidance
Mitigation generally focuses on treating workflow URLs as untrusted data throughout storage, rendering, and interaction handling.
Common defensive patterns include:
- Allowing only explicitly supported URL schemes and rejecting script-capable schemes
- Applying context-appropriate output encoding and safe DOM APIs
- Avoiding HTML interpretation or dynamic code execution for link handling
- Separating display text from navigation targets and validating both independently
- Requiring explicit trust boundaries for imported and shared workflows
- Applying least privilege to editor sessions and limiting accessible data and actions
- Using browser security controls such as a restrictive Content Security Policy where practical
How teams detect issues like this
Organizations can look for this class of issue through:
- Static analysis rules identifying unsafe DOM sinks, dynamic URL assignment, and insufficient scheme validation
- Code review checks for workflow data flowing into link, HTML, navigation, or event-handling paths
- Tests covering imported and shared workflows with untrusted URL values
- Policy enforcement that restricts accepted URL schemes at both validation and rendering boundaries
- Monitoring workflow content and UI behavior for unexpected script-capable links
Automated security review tools may help identify risky source-to-sink flows, but should be complemented by focused browser and integration testing.
