CVE-2026-21858: Critical Unauthenticated File Access Vulnerability in n8n "Ni8mare"
On January 7, 2026, fixes were released for a maximum severity vulnerability (CVE-2026-21858) impacting n8n, a workflow automation application primarily used with artificial intelligence. Labeled “Ni8mare” by the researchers who discovered it, the vulnerability allows unauthenticated remote threat actors to take over locally deployed instances via publicly accessible webhook and form endpoints.