CVE-2026-42235: n8n

Critical severity, CVSS 9.6. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• n8n n8n: before 1.123.32 (fixed in 1.123.32); from 2.17.0, before 2.17.4 (fixed in 2.17.4); version 2.18.0 only

Published 2026-05-04. Last modified 2026-06-17.