CVE-2026-42221 (GCVE-0-2026-42221)

Vulnerability from cvelistv5 – Published: 2026-05-04 20:09 – Updated: 2026-05-05 14:14
VLAI
Title
nginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim
Summary
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.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-05 14:06 UTC
CWE
  • CWE-306 - Missing Authentication for Critical Function
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7994 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
0xJacky nginx-ui Affected: >= 2.0.0, < 2.3.8
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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