Critical Zero-Day Flaw in n8n Workflow Automation Platform Enables Full System Takeover
Cybersecurity researchers have uncovered a maximum-severity vulnerability in n8n, a widely used workflow automation platform, that allows unauthenticated remote attackers to gain complete control over vulnerable instances. The flaw, tracked as CVE-2026-21858 (CVSS 10.0) and dubbed Ni8mare by Cyera Research Labs, was discovered by security researcher Dor Attias and reported on November 9, 2025.
The vulnerability stems from a Content-Type confusion flaw in n8n’s webhook and file-handling mechanism. By manipulating the Content-Type header, attackers can bypass authentication, extract sensitive files, forge administrator access, and execute arbitrary commands on the server. Unlike previous critical flaws in n8n—such as CVE-2025-68613 (RCE via code execution), CVE-2025-68668 (N8scape, sandbox bypass), and CVE-2026-21877 (unrestricted file upload)—this exploit does not require credentials, making it particularly dangerous.
Technical Breakdown
The issue lies in n8n’s parseRequestBody() function, which processes incoming webhook requests. When a request includes a multipart/form-data header, the system uses parseFormData() to handle file uploads, storing results in req.body.files. However, if an attacker sends a request with a different Content-Type, the system still invokes file-handling functions—such as copyBinaryFile()—without verifying the header, allowing manipulation of req.body.files.
This enables attackers to:
- Read arbitrary files (e.g.,
/home/node/.n8n/database.sqliteor/home/node/.n8n/config). - Extract admin credentials (user ID, email, hashed password) and encryption keys.
- Forge session cookies to bypass authentication and gain admin access.
- Achieve remote code execution (RCE) by creating workflows with malicious "Execute Command" nodes.
Affected Versions & Patch
The flaw impacts all n8n versions up to and including 1.65.0. A fix was released in version 1.121.0 on November 18, 2025, with subsequent updates (1.123.10, 2.1.5, 2.2.4, 2.3.0) also addressing the issue.
Impact & Risks
A compromised n8n instance can serve as a single point of failure, exposing API credentials, OAuth tokens, database connections, and cloud storage access—effectively handing attackers the "keys to everything" in an organization’s automation ecosystem. Researchers warn that the flaw’s low attack complexity and high impact make it a prime target for threat actors.
Organizations using n8n are urged to upgrade immediately and avoid exposing the platform to the internet without authentication. Temporary mitigations include disabling public webhook and form endpoints or restricting access to trusted networks.
Source: https://thehackernews.com/2026/01/critical-n8n-vulnerability-cvss-100.html
n8n cybersecurity rating report: https://www.rankiteo.com/company/n8n
"id": "N8N1767783939",
"linkid": "n8n",
"type": "Vulnerability",
"date": "11/2025",
"severity": "100",
"impact": "5",
"explanation": "Attack threatening the organization's existence"{'affected_entities': [{'customers_affected': 'All users of n8n versions prior '
'to 1.121.0',
'industry': 'Workflow Automation / SaaS',
'name': 'n8n',
'type': 'Software Vendor'}],
'attack_vector': 'Unauthenticated remote exploitation via crafted HTTP '
'requests',
'customer_advisories': 'Customers using affected n8n versions urged to '
'upgrade immediately and rotate exposed credentials.',
'data_breach': {'data_exfiltration': 'Possible via arbitrary file read and '
'RCE',
'file_types_exposed': ['Database files (.sqlite)',
'Configuration files (.config)'],
'personally_identifiable_information': 'User IDs, emails, '
'hashed passwords',
'sensitivity_of_data': 'High (secrets, authentication tokens, '
'PII)',
'type_of_data_compromised': ['API credentials',
'OAuth tokens',
'Database connections',
'Cloud storage access',
'Administrator credentials',
'Personally identifiable '
'information']},
'date_detected': '2025-11-09',
'date_publicly_disclosed': '2025-11-18',
'date_resolved': '2025-11-18',
'description': 'A maximum-severity security flaw in n8n, a popular workflow '
'automation platform, allows an unauthenticated remote '
'attacker to gain complete control over susceptible instances. '
'The vulnerability, tracked as CVE-2026-21858 (CVSS score: '
"10.0), exploits a 'Content-Type' confusion flaw to extract "
'sensitive secrets, forge administrator access, and execute '
'arbitrary commands on the server.',
'impact': {'brand_reputation_impact': 'High (public disclosure of critical '
'vulnerability)',
'data_compromised': 'Sensitive secrets, API credentials, OAuth '
'tokens, database connections, cloud storage '
'access, administrator credentials',
'identity_theft_risk': 'High (exposure of personally identifiable '
'information via database access)',
'operational_impact': 'Complete system compromise, unauthorized '
'access to connected services and data',
'systems_affected': 'n8n workflow automation instances (all '
'versions prior to and including 1.65.0)'},
'investigation_status': 'Completed (vulnerability patched and disclosed)',
'lessons_learned': 'Critical vulnerabilities in workflow automation platforms '
'can serve as a single point of failure for an '
"organization's entire digital infrastructure. Proper "
'input validation, authentication enforcement, and '
'least-privilege access are essential to mitigate such '
'risks.',
'post_incident_analysis': {'corrective_actions': ['Fixed in version 1.121.0 '
'by enforcing content-type '
'validation',
'Enhanced input validation '
'in file upload parser',
'Improved session '
'management to prevent '
'authentication bypass'],
'root_causes': ['Improper validation of '
"'Content-Type' header in webhook "
'and file handling mechanism',
'Insecure file-handling function '
'execution without content-type '
'verification',
'Global variable manipulation '
'allowing arbitrary file read']},
'recommendations': ['Upgrade to the latest patched version of n8n immediately',
'Avoid exposing n8n instances to the internet',
'Enforce authentication for all Forms and webhook '
'endpoints',
'Restrict or disable publicly accessible webhook and form '
'endpoints as a temporary workaround',
'Monitor for unauthorized access or unusual activity in '
'n8n instances',
'Rotate all secrets and credentials accessible via n8n '
'after patching'],
'references': [{'date_accessed': '2025-11-18', 'source': 'n8n Advisory'},
{'date_accessed': '2025-11-18',
'source': 'Cyera Research Labs'},
{'date_accessed': '2025-11-18', 'source': 'The Hacker News'}],
'response': {'communication_strategy': 'Public advisory published by n8n, '
'technical details shared with The '
'Hacker News',
'containment_measures': 'Release of patched version (1.121.0 and '
'later)',
'remediation_measures': 'Upgrade to patched versions (1.121.0, '
'1.123.10, 2.1.5, 2.2.4, or 2.3.0), '
'avoid exposing n8n to the internet, '
'enforce authentication for all Forms',
'third_party_assistance': 'Cyera Research Labs (vulnerability '
'discovery and reporting)'},
'stakeholder_advisories': 'Users advised to upgrade to patched versions and '
'implement recommended security measures.',
'title': 'Ni8mare: Critical Unauthenticated RCE Vulnerability in n8n '
'(CVE-2026-21858)',
'type': 'Remote Code Execution (RCE)',
'vulnerability_exploited': "Content-Type confusion flaw in n8n's webhook and "
'file handling mechanism (CVE-2026-21858)'}