10

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-21858

CVE-2026-21858: n8n Vulnerable to Unauthenticated File Access via Improper Webhook Request Handling

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.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-21858

CVE-2026-21858:

10

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
n8n	npm	< 1.121.0	1.121.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability allows unauthenticated file access through improper handling of webhook requests in form-based workflows. The analysis of the security patch identified that the root cause was the lack of Content-Type validation when processing file uploads. The patch consistently adds an assertion to enforce that the Content-Type must be multipart/form-data in the affected functions. The identified vulnerable functions, ChatTrigger.handleFormData, prepareFormReturnItem, and Webhook.handleFormData, are all directly involved in processing form data and file uploads from webhooks. The changes in the test files confirm that this was the intended fix for the vulnerability.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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