Ni8mare: n8n Vulnerability Gives Full Admin Access with One HTTP Header Change
100,000 servers. One HTTP header change. Full admin access. No password required. They call it “Ni8mare.” CVSS 10.0. The patch existed for 7 weeks. The release notes mentioned nothing. 😏
CVE-2026-21858. “Ni8mare” The name says it all.
n8n is a workflow automation platform. Think Zapier, but open source and self-hosted. Over 100 million Docker pulls. Used by Vodafone, Delivery Hero, StepStone. Thousands of enterprises run their entire automation infrastructure on it, with 400+ integrations connecting everything in one central hub.









