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Fencer Intel
medium 4.7

CVE-2026-126386 json

n8n before 1.123.89 Open Redirect via MCP OAuth Dynamic Client Registration

published 18d ago modified 2d ago also EUVD-2026-125179 , GHSA-rc3w-8jc8-7x3w

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository n8n-io/n8n. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
4.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits
0
none known

Summary

n8n before 1.123.89, 2.x before 2.45.5, 2.46.x before 2.46.1, and 3.x before 3.0.1 contains an open redirect vulnerability in the unauthenticated MCP OAuth dynamic client registration flow, which accepts arbitrary redirect_uri values via the /mcp-oauth/register endpoint. Attackers can send victims crafted /mcp-oauth/authorize URLs that redirect them to attacker-controlled sites before instance checks run, enabling phishing.

Patch / fix

  • npm n8n >= 1.123.89, >= 2.45.5, >= 2.46.1, >= 3.0.1
  • n8n-io n8n 1.123.89, 2.45.5, 2.46.1, 3.0.1

Is CVE-2026-126386 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
CNA 3.1 4.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 4.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm n8n
<1.123.89
<2.46.1
<2.45.5
<3.0.1
>= 1.123.89
>= 2.46.1
>= 2.45.5
>= 3.0.1

Affected products

  • n8n-io n8n

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of n8n-io/n8n published their own advisory on GitHub. Reviewed sources take precedence over it.