CVE-2026-21858Public exploitNetwork attack vector

Unauthenticated file read via forged form file paths

Published Jan 7, 2026 · Updated Jan 7, 2026

Improper input validation in n8n 1.65.0 and later before 1.121.0 allows remote attackers to read server files through public Form workflows. formWebhook calls prepareFormReturnItem without requiring multipart form data, so a JSON body can supply req.body.files filepath values that copy arbitrary local paths. Exploitation requires a reachable Form workflow that handles file uploads; copied content reaches downstream nodes and can expose the local database and signing secret, enabling instance takeover.

CVSS severity10.0
Critical
EPSS probability78.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in n8n 1.65.0 and later before 1.121.0 allows remote attackers to read server files through public Form workflows. formWebhook calls prepareFormReturnItem without requiring multipart form data, so a JSON body can supply req.body.files filepath values that copy arbitrary local paths. Exploitation requires a reachable Form workflow that handles file uploads; copied content reaches downstream nodes and can expose the local database and signing secret, enabling instance takeover.

The record

CVE
CVE-2026-21858
Published
Jan 7, 2026
Updated
Jan 7, 2026
Vendor
n8n
Product
n8n
Classifications
CWE-20, T1190, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.121.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

n8n · n8nversion=< 1.121.0

Published CVSS scores

10.0GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1190Exploit Public-Facing Application
T1005Data from Local System

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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