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.
History

Wed, 06 May 2026 17:30:00 +0000

Type Values Removed Values Added
First Time appeared Nginxui
Nginxui nginx Ui
CPEs cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:*
Vendors & Products Nginxui
Nginxui nginx Ui

Tue, 05 May 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 04 May 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared 0xjacky
0xjacky nginx-ui
Vendors & Products 0xjacky
0xjacky nginx-ui

Mon, 04 May 2026 20:30:00 +0000

Type Values Removed Values Added
Description 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.
Title nginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim
Weaknesses CWE-306
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-05-04T20:09:37.308Z

Updated: 2026-05-05T14:14:11.906Z

Reserved: 2026-04-25T05:04:37.029Z

Link: CVE-2026-42221

cve-icon Vulnrichment

Updated: 2026-05-05T14:11:15.749Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-04T21:16:32.023

Modified: 2026-05-06T17:17:57.437

Link: CVE-2026-42221

cve-icon Redhat

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