{"id":"CVE-2026-42221","state":"PUBLISHED","title":"nginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim","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.","publishedAt":"2026-05-04T20:09:37.308Z","updatedAt":"2026-05-05T14:14:11.906Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["0xJacky nginx-ui"],"affected":[{"vendor":"0xJacky","product":"nginx-ui","versions":[{"version":">= 2.0.0, < 2.3.8","status":"affected"}]}],"references":["https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp","https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8"],"weaknesses":["CWE-306"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/42xxx/CVE-2026-42221.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42221","state":"PUBLISHED","datePublished":"2026-05-04T20:09:37.308Z","dateUpdated":"2026-05-05T14:14:11.906Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-25T05:04:37.029Z"},"containers":{"cna":{"title":"nginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"0xJacky","product":"nginx-ui","versions":[{"version":">= 2.0.0, < 2.3.8","status":"affected"}]}],"references":[{"url":"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp","name":"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8","name":"https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.8","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":8.1,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-306","lang":"en","description":"CWE-306: Missing Authentication for Critical Function","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-04T20:09:37.308Z"},"source":{"advisory":"GHSA-h27v-ph7w-m9fp","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-h27v-ph7w-m9fp","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-05T14:06:26.362325Z","id":"CVE-2026-42221","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-05T14:14:11.906Z"}}]}}}