Actively Exploited nginx-ui Flaw (CVE-2026-33032) Enables Full Nginx Server Takeover
Apr 15, 2026
Web Security / Vulnerability
A recently disclosed critical security flaw impacting nginx-ui, an open-source, web-based Nginx management tool, has come under active exploitation in the wild. The vulnerability in question is CVE-2026-33032 (CVSS score: 9.8), an authentication bypass vulnerability that enables threat actors to seize control of the Nginx service. It has been codenamed MCPwn by Pluto Security. "The nginx-ui MCP (Model Context Protocol) integration exposes two HTTP endpoints: /mcp and /mcp_message," according to an advisory released by nginx-ui maintainers last month. "While /mcp requires both IP whitelisting and authentication (AuthRequired() middleware), the /mcp_message endpoint only applies IP whitelisting -- and the default IP whitelist is empty, which the middleware treats as 'allow all.'" "This means any network attacker can invoke all MCP tools without authentication, including restarting nginx, creating/modifying/deleting nginx configuration files, and t...