Improper Validation of Specified Type of Input Affecting n8n package, versions >=1.65.0 <1.121.0
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-N8N-14908212
- published14 Jan 2026
- disclosed7 Jan 2026
- creditDor Attias
Introduced: 7 Jan 2026
CVE-2026-21858 (opens in a new tab)How to fix?
Upgrade n8n to version 1.121.0 or higher.
Overview
n8n is a n8n Workflow Automation Tool
Affected versions of this package are vulnerable to Improper Validation of Specified Type of Input that is passed to the handleFormData() function. An attacker can gain unauthorized access to files on the underlying server by requests with unexpected content-type values to exposed webhook listeners. This allows the attacker to make arbitrary file contents available via means such as the chat interface. Sensitive cookie values retrieved can then be used to bypass authentication and further compromise of the application and underlying system.
Note:
For users using the main n8n package it is recommended to upgrade to n8n@1.121.0.
Workaround
This vulnerability can be mitigated by restricting or disabling publicly accessible Form webhook.