Information disclosure in n8n - CVE-2026-21858
Published: February 9, 2026 / Updated: April 17, 2026
Vulnerability identifier: #VU122486
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-21858
CWE-ID: CWE-200
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vulnerability details
The vulnerability allows a remote attacker to gain access to potentially sensitive information.
The vulnerability exists due to a logic error in certain form-based workflows. A remote non-authenticated attacker can view contents of files on the server.
Affected software
n8n
How to mitigate CVE-2026-21858
Install updates from vendor's website.
n8n - update to 1.121.0
Links to Public Exploits and PoC-codes
- Exploit #12595 - PoC-CVE-2026-21858 (Proof-of-concept exploit for CVE-2026-21858 (ni8mare) impacting n8n versions < 1.121.0) (April 17, 2026)
- Exploit #12401 - Ni8mare (Comprehensive vulnerability detection tool for n8n workflow automation instances. Detects the critical CVE-2026-21858 vulnerability (CVSS 10.0) without performing any exploitation.) (February 13, 2026)