0xJacky nginx-ui up to 2.3.5 Model Context Protocol /mcp AuthRequired missing authentication

Summaryinfo

A vulnerability classified as critical has been found in 0xJacky nginx-ui up to 2.3.5. This affects the function AuthRequired of the file /mcp of the component Model Context Protocol. This manipulation causes missing authentication. This vulnerability is handled as CVE-2026-33032. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical was found in 0xJacky nginx-ui up to 2.3.5. Affected by this vulnerability is the function AuthRequired of the file /mcp of the component Model Context Protocol. The manipulation with an unknown input leads to a missing authentication vulnerability. The CWE definition for the vulnerability is CWE-306. The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Nginx UI is a web user interface for the Nginx web server. In versions 2.3.5 and prior, the nginx-ui MCP (Model Context Protocol) integration exposes two HTTP endpoints: /mcp and /mcp_message. 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 triggering automatic config reloads - achieving complete nginx service takeover. At time of publication, there are no publicly available patches.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-33032 since 03/17/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 03/30/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Web Server

Vendor

• 0xJacky

Name

• nginx-ui

Version

• 2.3.0
• 2.3.1
• 2.3.2
• 2.3.3
• 2.3.4
• 2.3.5

Website

• Product: https://github.com/0xJacky/nginx-ui/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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