CVE-2026-126386 · AI agents & MCP
NO FIX YET · SEE WHAT TO DO
n8n's MCP OAuth dynamic client registration accepts any redirect_uri without checks, so an unauthenticated attacker can build /mcp-oauth/authorize links that send victims to attacker-controlled sites. The result is phishing that starts from a trusted n8n URL.
first public Oct 28, 2026 · 1 source
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Teams that run a self-hosted n8n instance with the MCP OAuth flow reachable from the internet are exposed, because the registration endpoint accepts unauthenticated requests. Instances on the affected version ranges that do not expose MCP OAuth endpoints are less exposed, and managed or fixed-version instances are not affected.
Not affected if fixed-version, managed-hosting
Who cares mcp, n8n, self-hosted
n8n --version or the instance's About page; versions below 1.123.89, 2.45.5 (2.x line), 2.46.1 (2.46.x line) or 3.0.1 are affected./mcp-oauth/register are reachable on the instance.1.123.89n8n 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.
This page as .md · .json · 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
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2.45.52.46.13.0.1