CVE-2026-42221

Nginx UI is a web user interface for the Nginx web server. From version 2.0.0 to before version 2.3.8, an unauthenticated network attacker can claim the initial administrator account on a fresh nginx-ui instance during the first-run setup window. The public /api/install endpoint is reachable without authentication, and the request-encryption flow only protects payload confidentiality in transit; it does not authenticate who is allowed to perform installation. A remote attacker who reaches the service before the legitimate operator can set the admin email, username, and password, causing permanent initial-instance takeover. This issue has been patched in version 2.3.8.

The following products are affected by CVE-2026-42221 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-42221.

URL	Resource
https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8
https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp