{"id":"CVE-2026-42221","summary":"nginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim","details":"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.","aliases":["GHSA-h27v-ph7w-m9fp","GO-2026-5412"],"modified":"2026-07-15T01:49:21.449896119Z","published":"2026-05-04T20:09:37.308Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42221.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-306"]},"references":[{"type":"WEB","url":"https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8"},{"type":"ADVISORY","url":"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42221.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42221"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/0xjacky/nginx-ui","events":[{"introduced":"daee3ac7ade1162805b3af07807e2f4dc2affaf5"},{"fixed":"7864e378f5cf8013c4df38c15e57480f5c2db1d7"}],"database_specific":{"extracted_events":[{"introduced":"2.0.0"},{"fixed":"2.3.8"}],"source":["AFFECTED_FIELD","CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:*"}}],"versions":["v2.3.7","v2.3.6","v2.3.5","v2.3.4","v2.3.3","v2.3.2","v2.3.1","v2.3.0","v2.2.1","v2.2.0-patch.1","v2.2.0","v2.1.17","v2.1.16","v2.1.15","v2.1.14","v2.1.13","v2.1.12","v2.1.11","v2.1.10","v2.1.9","v2.1.8","v2.1.7","v2.1.6","v2.1.5","v2.1.4-patch.1","v2.1.4","v2.1.3","v2.1.2","v2.1.1","v2.1.0-patch.1","v2.1.0","v2.1.0-rc.3","v2.1.0-rc.2","v2.1.0-rc.1","v2.1.0-beta.1","v2.0.2","v2.0.1","v2.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42221.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}