A severe security vulnerability has been discovered in n8n, the popular workflow automation platform, that poses an urgent threat to organizations worldwide. Identified as CVE-2026–21858, this critical flaw has received the maximum CVSS severity score of 10.0, signaling the highest possible risk level for affected systems.

Understanding the Vulnerability

At its core, CVE-2026–21858 exploits a content-type confusion bug within n8n’s file handling mechanisms. This seemingly technical issue creates a dangerous opening that attackers can leverage with alarming ease and devastating consequences.

The vulnerability allows unauthenticated attackers — meaning those without any legitimate credentials or access — to bypass standard file-upload restrictions by manipulating HTTP request headers. This manipulation tricks the system into accepting malicious file uploads that would normally be blocked by security controls.

The Attack Chain

What makes this vulnerability particularly dangerous is how attackers can chain multiple exploitation techniques:

Initial Access: By exploiting the content-type confusion, threat actors gain the ability to read sensitive internal files…