CVE-2026-110849 in n8n
Summary
by MITRE • 10/15/2026
n8n before 1.123.83, 2.41.4, and 2.42.1 contains a stored cross-site scripting vulnerability in the file-preview modal, which re-publishes binary data as an unsandboxed same-origin blob URL. A member who uploads a crafted item can run script in the n8n origin of whoever previews it, typically the owner, and act with their session.
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Analysis
by VulDB Data Team • 10/15/2026
The identified vulnerability represents a critical stored cross-site scripting (XSS) flaw within the file-preview functionality of n8n versions prior to 1.123.83, 2.41.4, and 2.42.1. This security defect stems from an improper neutralization of special elements during data processing, specifically categorized under CWE-79 in the Common Weakness Enumeration standard. The core technical issue lies in how the application handles binary file uploads for preview purposes. When a user uploads a file containing malicious script payloads embedded within its metadata or structure, the system processes this content without adequate sanitization. Instead of rendering the file safely through an iframe with strict sandboxing policies or converting it to a safe format like base64 data URIs that restrict execution contexts, n8n constructs and re-publishes the binary data as an unsandboxed blob URL. This approach effectively treats the uploaded malicious content as executable code within the context of the web application itself rather than isolating it in a separate origin with restricted permissions.
The operational impact of this vulnerability is severe due to its stored nature, which means the payload persists on the server and affects multiple users over time. An attacker who possesses member-level access can upload a crafted item containing JavaScript code designed to exploit the browser's trust in the n8n domain. When another user, typically the workflow owner or an administrator with higher privileges, opens this file for preview within the application interface, their browser executes the malicious script as if it originated from the legitimate n8n server. Because blob URLs generated by the same origin are treated as part of that origin's security context, the injected scripts inherit full access to the session cookies, local storage, and other sensitive data associated with the victim’s active session. This allows the attacker to perform actions on behalf of the victim without their knowledge or consent, effectively bypassing authentication mechanisms for any subsequent requests made by the browser.
This attack vector aligns closely with MITRE ATT&CK technique T1059.007, which covers JavaScript execution in web browsers, and specifically exploits the lack of proper output encoding and context-aware validation that characterizes CWE-83, Improper Neutralization of Script-Related HTML Tags in a Web Page. The consequence is not merely visual defacement but full session hijacking potential. An attacker can exfiltrate sensitive workflow configurations, steal authentication tokens, or manipulate automation workflows to execute unauthorized actions such as sending malicious emails, accessing connected third-party services, or modifying system settings. Since the vulnerability relies on social engineering tactics where a victim voluntarily previews a file uploaded by an adversary, it bypasses many traditional perimeter defenses that focus solely on external network intrusion attempts.
Mitigation strategies must prioritize immediate version upgrades to n8n 1.123.83, 2.41.4, or later releases where this flaw has been addressed through stricter input validation and secure rendering practices for file previews. In environments where upgrading is not immediately feasible, administrators should implement strict Content Security Policy headers that restrict the execution of inline scripts and limit blob URL generation to trusted origins only. Additionally, enabling sandbox attributes on any iframe elements used for previewing user-uploaded content can significantly reduce the blast radius by preventing access to parent window objects and cookies. Regular security audits focusing on file upload handlers are also recommended to ensure that binary data is never interpreted as executable code within the application's primary domain context.