n8n: Prior to versions 1.123.32, 2.17.4, and 2.18.1, an unauthenticated attacker could register a…
n8n
- Severity
- Critical, CVSS 9.6
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- Record
- CVE-2026-42235
- Affects
- n8n
- Known exploited
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- May 4, 2026
- Source last modified
- June 17, 2026
Description
n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, an unauthenticated attacker could register a malicious MCP OAuth client with a crafted client_name. If a victim user authorized the OAuth consent dialog and a second user subsequently revoked that access, a toast notification would render the injected script. Clicking the link would execute arbitrary JavaScript in the victim's authenticated n8n browser session, enabling credential and session token theft, workflow manipulation, or privilege escalation. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.
Description quoted from the NVD record.
Who is affected
n8n, an open source tool for automating tasks by connecting apps and services, has this flaw in versions before 1.123.32, 2.17.4 and 2.18.1. It sits in the feature that lets outside AI tools ask for permission to connect to n8n. An attacker without an account could register a harmful connection request. If one user approves it and another user later removes that access, a pop-up message shows a link carrying the attacker's code. Clicking it runs that code in the victim's logged-in n8n session, letting the attacker steal passwords and login sessions, change workflows or gain more access. This flaw is rated Critical.
What to do
- The person who installed or looks after n8n for your organization, or the IT provider who manages it, should act on this flaw.
- Check which version of n8n you are running so you know which update applies.
- Update n8n to version
1.123.32,2.17.4or2.18.1, or any later release, choosing the fixed version for the version line you already use. - If an IT provider or vendor runs n8n for you, send them this advisory and ask when the update will be done.
Analysis written from the source record as of June 17, 2026 and reviewed before publishing.