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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.

PUBLISHED Reserved 2026-04-25 | Published 2026-05-04 | Updated 2026-05-05 | Assigner GitHub_M




HIGH: 8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem types

CWE-306: Missing Authentication for Critical Function

Product status

>= 2.0.0, < 2.3.8
affected

References

github.com/...inx-ui/security/advisories/GHSA-h27v-ph7w-m9fp exploit

github.com/...inx-ui/security/advisories/GHSA-h27v-ph7w-m9fp

github.com/0xJacky/nginx-ui/releases/tag/v2.3.8

cve.org (CVE-2026-42221)

nvd.nist.gov (CVE-2026-42221)

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