CVE-2026-21858

Name of the Vulnerable Software and Affected Versions n8n versions 1.65.0 through 1.120.x

Description A critical issue in the workflow automation platform allows unauthenticated remote attackers to gain full control over self-hosted instances. The flaw stems from a Content-Type mismatch in how the platform processes form-based webhook requests. Specifically, the middleware determines the parser based on the Content-Type header, but the Form Webhook Node fails to validate this header. An attacker can change the Content-Type from multipart/form-data to application/json and send a crafted payload to override the req.body.files object, including the file path. This enables arbitrary file reads, allowing attackers to access the local SQLite database and configuration files containing encryption secrets. By using these files, an attacker can forge an admin session cookie to authenticate without credentials and subsequently use the Execute Command node to achieve remote code execution. Approximately 100,000 servers worldwide are potentially affected. Real-world reconnaissance campaigns have been observed using a specialized user agent n8n-scanner/1.0 to identify vulnerable endpoints via dictionary-based path enumeration.

Recommendations Update n8n to version 1.121.0 or later. Restrict or disable publicly accessible webhook and form endpoints. Avoid exposing the instance directly to the internet without a VPN or additional authentication. Require authentication on all public forms. Rotate all stored credentials and API keys if a prior compromise is suspected.