CVE-2026-42222: Nginx-UI: Unauthenticated first-boot instance claim via POST /api/install allows remote bootstrap takeover

CVE-2026-42222 · Severity: high · CVSS 8.1 · Published 2026-05-04

Nginx UI is a web user interface for the Nginx web server. In version 2.3.5, an unauthenticated bootstrap takeover exists in nginx-ui during the initial installation window exposed by POST /api/install. At time of publication no public patches are available.

Technologies: github.com/0xJacky/Nginx-UI (Go), Nginxui Nginx Ui. Vendors: Go, Nginxui.

Quick answers

Is CVE-2026-42222 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-42222 being exploited in the wild.
How severe is CVE-2026-42222?
High severity, with a CVSS score of 8.1, published 4 May 2026.
Which products and versions are affected?
github.com/0xJacky/Nginx-UI (Go) SEMVER:introduced=0.
Is there a fix for CVE-2026-42222?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-42222?
Check whether you run github.com/0xJacky/Nginx-UI (Go) or Nginxui Nginx Ui at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Affected products

  • github.com/0xJacky/Nginx-UI (Go) SEMVER:introduced=0
  • Nginxui Nginx Ui

Identifiers

  • CVE-2026-42222
  • GHSA-mxqh-q9h6-v8pq
  • GO-2026-5521

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.