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GHSA-hh89-3r9w-qj3j

HighCVSS 8.7 / 10
Published Sep 10, 2026·Last modified Sep 10, 2026
Affected Components(2)
npm logon8n
2.38.0 – 2.38.2
npm logon8n
< 2.37.7
Description

Impact

The OAuth Dynamic Client Registration endpoints validated field sizes only for redirect_uris, leaving client_name and grant_types bounded by presence checks alone. An unauthenticated remote caller could submit arbitrarily large values in either field and have them persisted to the database. Repeated registration therefore grew persistent storage without limit and without any account on the instance. The patch caps client_name at its column length and limits grant_types to the grant types the server actually implements, with the array capped at that count.

Patches

The issue has been fixed in n8n versions 2.37.7 and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

  • Restrict network access to the n8n instance so that only trusted clients can reach it.
  • Place the instance behind a reverse proxy configured to enforce strict request body size limits below the default 16 MiB.
  • Monitor database size for unexpected growth and audit the oauth_clients table for anomalous entries.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

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Risk Scores
Base Score
8.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.61%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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