CVE-2026-103249 in n8n
Summary
by MITRE • 10/01/2026
n8n versions before 1.123.80, from 2.0.0 before 2.39.6, and from 2.40.0 before 2.40.1 contain a stored DOM cross-site scripting vulnerability in Resource Locator parameter dropdown link handling. Workflow authors can inject malicious script URLs that execute arbitrary JavaScript in the editor origin when other users open the node dropdown and click the external-link icon, with the payload persisting across workflow imports and shares.
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Analysis
by VulDB Data Team • 10/01/2026
The identified security flaw resides within n8n versions prior to 1.123.80, as well as specific ranges of version 2 including those before 2.39.6 and between 2.40.0 up to but not including 2.40.1. This vulnerability is classified as a stored cross-site scripting issue specifically affecting the Resource Locator parameter dropdown link handling mechanism within the workflow editor interface. The core technical deficiency involves insufficient sanitization or validation of user-supplied input when processing external links associated with node parameters, allowing malicious actors to inject executable JavaScript payloads directly into the application's DOM structure through legitimate configuration fields.
The operational impact stems from the persistence nature of this vulnerability. Unlike reflected XSS attacks that require immediate interaction for payload delivery, stored vulnerabilities persist within the application state or database. In this context, a workflow author can embed a malicious script URL during the creation or modification of a workflow node. This injected code remains embedded in the workflow definition and will execute whenever another user opens the specific node dropdown menu and interacts with the external-link icon. Because n8n workflows are frequently shared, imported, and collaborated upon across teams, this persistence ensures that the vulnerability can be triggered by multiple victims without requiring further action from the initial attacker who created the malicious workflow configuration.
From a threat modeling perspective, this flaw aligns closely with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific vector involves stored input that is later rendered in a browser context without proper encoding or escaping. Furthermore, the attack pattern corresponds to MITRE ATT&CK technique T1059, specifically Command and Scripting Interpretation via JavaScript execution within a web application environment. By executing arbitrary scripts in the editor origin, an attacker gains the ability to perform actions on behalf of the victim user, potentially leading to session hijacking, credential theft through keylogging or form submission interception, or defacement of the workflow interface depending on the specific payload delivered and the permissions granted to the affected users within the n8n instance.
Mitigation strategies must prioritize immediate version upgrades for all affected deployments. Administrators should upgrade n8n to version 1.123.80 or later, or if using major version two, ensure an update to at least version 2.40.1 or any subsequent release that addresses this specific input validation gap. For environments where immediate patching is not feasible due to operational constraints, temporary mitigations should include restricting access to workflow creation and editing capabilities to trusted users only, thereby reducing the attack surface for initial payload injection. Additionally, implementing a Content Security Policy with strict script-src directives can help mitigate the impact of any successfully injected scripts by preventing unauthorized execution contexts within the browser environment. Regular security audits of shared workflows are also recommended to detect any pre-existing malicious configurations before they trigger against other users in the organization.