CVE-2026-21858: Maximum-severity n8n flaw lets randos run your automation server


A maximum-severity bug in the popular automation platform n8n has left an estimated 100,000 servers wide open to complete takeover, courtesy of a flaw so bad it doesn’t even require logging in. The vulnerability, uncovered by researchers at security outfit Cyera, carries a CVSS score of 10.0 and has been dubbed “ni8mare” for good reason.

Tracked as CVE-2026-21858, the flaw allows an unauthenticated attacker to execute arbitrary code on vulnerable systems, effectively handing over complete control of the affected environment. There is no workaround other than patching, and users are urged to upgrade to n8n version 1.121.0 or later.

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Source: The Register News


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