{"cve":"CVE-2026-42221","nvd":{"published":"2026-05-04T21:16:32.023","modified":"2026-10-26T19:10:00.163","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-306"],"references":["https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8","https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp","https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp"],"products":["nginxui:nginx_ui"],"source":"nvd","synced_at":"2026-10-26T19:31:02.781428341+00:00"},"epss":{"cve":"CVE-2026-42221","score":0.01342,"percentile":0.71153,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-h27v-ph7w-m9fp","url":"https://osv.dev/vulnerability/GHSA-h27v-ph7w-m9fp","summary":"Nginx-UI: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim","modified":"2026-06-25T23:11:04.578182544Z","packages":[{"ecosystem":"Go","name":"github.com/0xJacky/Nginx-UI","purl":"pkg:golang/github.com/0xJacky/Nginx-UI","ranges":[">=2.0.0 <2.3.8"],"fixed":["2.3.8"]}]},{"id":"GO-2026-5412","url":"https://osv.dev/vulnerability/GO-2026-5412","summary":"Nginx-UI: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim in github.com/0xJacky/Nginx-UI","modified":"2026-06-25T23:00:54.621523594Z","packages":[{"ecosystem":"Go","name":"github.com/0xJacky/Nginx-UI","purl":"pkg:golang/github.com/0xJacky/Nginx-UI","ranges":["all versions"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}