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Nginx UiWeb server / proxy · Nginxui

CVE-2026-33032

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-30
Fix available
A fix is available. Upgrade to after 2.3.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Nginx UI versions 2.3.5 and prior expose an MCP integration with two endpoints where /mcp requires both IP whitelisting and authentication via AuthRequired() middleware, but /mcp_message only enforces IP whitelisting. The default empty IP whitelist is treated as 'allow all', enabling any network attacker to invoke all MCP tools without credentials and achieve full nginx service takeover through config manipulation and service restarts.

MitigationApply the AuthRequired() middleware to the /mcp_message endpoint and change the default whitelist behavior to deny all instead of allow all when empty. Until a patch is released, consider network-level blocking of /mcp_message or disabling the MCP integration entirely.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nginx UiWeb server / proxy
Affected:<= 2.3.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Nginx UI version
    Locate the Nginx UI version in the application interface, configuration files, or by querying the service binary. Common locations include the admin dashboard 'About' page, version info in container metadata, or the binary executable.
    Affected if The installed version is 2.3.5 or any earlier version.
  2. Verify MCP integration is present and enabled
    Check if the MCP (Model Context Protocol) integration feature is enabled in the Nginx UI configuration. This is typically found in the application settings, configuration file, or by observing the presence of /mcp and /mcp_message endpoints.
    Affected if MCP integration is enabled and the /mcp_message endpoint exists in the service.
  3. Confirm /mcp_message lacks authentication middleware
    Review the Nginx UI source code, API route definitions, or middleware configuration to verify whether the /mcp_message endpoint enforces authentication (AuthRequired()) versus only IP whitelisting. This may require examining the route handlers or proxy configuration.
    Affected if The /mcp_message endpoint does not require authentication and only enforces IP whitelisting.
  4. Inspect IP whitelist configuration
    Examine the IP whitelist settings for the MCP endpoints in the Nginx UI configuration. Look for the whitelist parameter that controls access to /mcp and /mcp_message. Determine whether the whitelist is empty or set to permit all addresses.
    Affected if The IP whitelist for /mcp_message is empty or configured to allow all addresses (0.0.0.0/0 or similar).

You are affected if running Nginx UI version 2.3.5 or prior with MCP integration enabled where the /mcp_message endpoint is accessible without authentication and the IP whitelist defaults to allow all when empty.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.3.5
Interim mitigation

Apply the AuthRequired() middleware to the /mcp_message endpoint and change the default whitelist behavior to deny all instead of allow all when empty. Until a patch is released, consider network-level blocking of /mcp_message or disabling the MCP integration entirely.

Recommended fix Moderate confidence
  1. Add explicit IP restrictions to the nginx-ui configuration to limit access to the /mcp and /mcp_message endpoints to trusted IP addresses only
  2. Configure the IP whitelist in nginx-ui with specific trusted IP ranges (e.g., internal network IPs or specific admin IPs) - do not leave it empty
  3. If nginx-ui is exposed to the internet, consider using network-level firewall rules or nginx reverse proxy ACLs to restrict access to trusted IPs
  4. Restart nginx-ui after applying configuration changes to ensure restrictions take effect
  5. Audit nginx configuration files for any unauthorized changes that may have occurred during any potential exploitation

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nginx Ui Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33032 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data