Threat Intelligence / CVE / CVE-2026-33032

CVE-2026-33032 — Nginxui Nginx Ui

CVSS v3.1 9.8 (CRITICAL) · EPSS 9.3% (higher than 92.7% of all scored CVEs) · Priority 8.6/10 · Published 2026-03-30

As of 2026-04-16, CVE-2026-33032 is a CRITICAL-severity vulnerability in Nginxui Nginx Ui, CVSS v3.1 9.8, EPSS 9.3% (92.7th percentile). Threadlinqs Intelligence links 3 tracked threat campaigns to CVE-2026-33032, most recently “Internet-Wide Reconnaissance Scans Target MCP Servers and Claude/Cursor AI-Agent Credentials”.

Last updated: 2026-04-16

What is CVE-2026-33032?

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 record classifies CVE-2026-33032 under weakness class CWE-306. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 166 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST): 9.3% probability of exploitation in the next 30 days, higher than 92.7% of all scored CVEs
CISA KEV: Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority: 8.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published: 2026-03-30, last modified 2026-04-16

Is CVE-2026-33032 being exploited?

It currently carries a trending score of 33 in the Threadlinqs vulnerability feed.

Affected products and versions

Nginxui: Nginx Ui

How to fix CVE-2026-33032

Vendor advisory: https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h6c2-x2m2-mwhf. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2026-33032

3 tracked threats in the Threadlinqs corpus reference CVE-2026-33032, either in the campaign’s CVE list or as an indicator on the campaign record.

Internet-Wide Reconnaissance Scans Target MCP Servers and Claude/Cursor AI-Agent Credentials — MEDIUM · 2026-07-13
Nginx UI Authentication Bypass via Unauthenticated MCP Endpoint (CVE-2026-33032) — CRITICAL · 2026-04-17
CVE-2026-33032 (MCPwn): nginx-ui Middleware Bypass Enabling Unauthenticated Configuration Write and Full Web Server Takeover — CRITICAL · 2026-04-16

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2026-33032 are available via the Threadlinqs MCP server (Purple tier). View plans →

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