CVE-2026-33032 (MCPwn): Critical Nginx UI Authentication Bypass Actively Exploited

A critical authentication bypass in nginx-ui (CVE-2026-33032, CVSS 9.8) is under active exploitation in the wild. Dubbed “MCPwn” by Pluto Security, the flaw lets unauthenticated attackers seize full control of the Nginx service—including the ability to restart, create, modify, and delete configuration files—without any valid credentials.

nginx-ui is an open-source web-based management interface for Nginx that recently added Model Context Protocol (MCP) support. The MCP integration appears to have introduced the authentication bypass path now being weaponized for full server takeover.

Organizations running nginx-ui should patch immediately and treat any internet-facing instance as potentially compromised. Review nginx-ui access logs for unauthenticated API calls and audit recently modified Nginx configurations for unauthorized changes.