What is the CVSS score of CVE-2026-21858?

CVE-2026-21858 has a CVSS 3.1 base score of 10.0 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N. EPSS exploitation probability: 7.1%.

Is there a public PoC exploit available for CVE-2026-21858?

Yes, a public proof-of-concept exploit is available for CVE-2026-21858. Prioritise patching immediately. EPSS: 7.1%.

How to fix or mitigate CVE-2026-21858?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Monitor vendor channels for patch availability.

N8n CVE-2026-21858

CRITICAL

Improper Input Validation (CWE-20)

2026-01-08 security-advisories@github.com

GHSA-v4pr-fm98-w9pg

Information Disclosure Path Traversal Node.js LFI N8n

10.0

CVSS 3.1 · GitHub Advisory

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Send crafted HTTP request to vulnerable workflow endpoint
Exploit

Exploit form-based workflow execution without authentication
Execution

Access arbitrary files on server
Impact

Exfiltrate sensitive data

Vulnerability Assessment

Weakness	CWE CWE-20 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V2 - Validation and Business Logic Input validation, allowlisting
Exploitation Conditions	n8n versions 1.65.0 through 1.120.x with form-based workflows enabled. No authentication required; remote unauthenticated attacker can exploit default configurations by targeting workflow endpoints that process untrusted form inputs without proper validation.
Impact	CVSS 10.0 (Critical). No auth, network vector, low complexity, scope change. PoC available. n8n stores credentials for dozens of integrated services – compromise exposes the entire automation infrastructure. EPSS 7.1%.
Exploit ScenarioDerived	An attacker discovers an n8n instance, triggers a vulnerable form-based workflow that reads /app/.env, obtaining database passwords, API keys for connected services (Slack, GitHub, cloud providers), and n8n's encryption key for all stored credentials.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

Patch available 7.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

n8n workflow automation (1.65.0 to 1.121.0) allows unauthenticated file access through form-based workflows. A critical CVSS 10.0 vulnerability enabling remote attackers to read sensitive files from the server, with potential for further compromise. PoC available.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 10.0

n8n allows unauthenticated file access through form-based workflows, enabling sensitive data exposure with CVSS 10.0 and scope change.

RemediationAI

Update to n8n 1.121.1 or later. Never expose n8n to the internet without authentication. Rotate all credentials stored in n8n if exposure is suspected.

Affected Packages

npm n8n fix: 1.121.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in npm

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Form-based workflows in n8n can be crafted to access local files on the server (CWE-20). Since these workflows can be triggered by unauthenticated users, any sensitive file (environment variables, database credentials, private keys) is accessible. The scope change reflects that n8n servers typically have access to connected service credentials.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 10.0 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

PoC Detected

Jan 16, 2026 - 19:31 vuln.today

Public exploit code

CVE Published

Jan 08, 2026 - 00:15 nvd

CRITICAL 10.0

DescriptionGitHub Advisory

n8n is an open source workflow automation platform. Versions starting with 1.65.0 and below 1.121.0 enable an attacker to access files on the underlying server through execution of certain form-based workflows. A vulnerable workflow could grant access to an unauthenticated remote attacker, resulting in exposure of sensitive information stored on the system and may enable further compromise depending on deployment configuration and workflow usage. This issue is fixed in version 1.121.0.

Executive ViewAI

Why It Matters

Organizations using n8n face critical risk from CVE-2026-21858, a input validation vulnerability rated CVSS 10.0. Successful exploitation could critically impact the confidentiality, integrity, and availability of affected systems. Proof-of-concept code is publicly available, increasing the risk of exploitation. Organizations should apply vendor updates immediately when available and implement compensating controls in the interim.

Business Impact: Severe

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score

7.1%

Top 9% exploitable

Exploit

POC

Public exploit code exists

Data Quality

4 sources

Confidence: Medium

NVD

CVE.org

EPSS POC (1)

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC Yes

EPSS 7.1%

Patch available Yes

Active threat No

Deciding rule

CRITICAL severity + public POC available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Out-of-Cycle

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +7

CVSS: +50

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Local File Inclusion HIGH

Local File Inclusion vulnerabilities occur when an application accepts user-controlled input to specify which file should be loaded or executed, typically through functions like PHP's `include()`, `require()`, or `fopen()`.

Path Traversal HIGH

Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.