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TI-2026-30542 Aliases CVE-2026-42221GHSA-h27v-ph7w-m9fp

nginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin Claim

Priority HIGH 76CWE-306Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-306.

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.01342 71st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed nginx-ui (0xJacky): 2.3.8github.com/0xJacky/Nginx-UI (Go): 2.3.8

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
0xJackynginx-ui2.0.0 to before 2.3.82.3.8Patch availableCNA
—github.com/0xJacky/Nginx-UI (Go)2.0.0 to before 2.3.82.3.8Patch availableGHSA-h27v-ph7w-m9fp
  • nginx-ui Vendor0xJacky Affected 2.0.0 to before 2.3.8 Fixed in 2.3.8 Patch available CNA
  • github.com/0xJacky/Nginx-UI (Go) Vendor— Affected 2.0.0 to before 2.3.8 Fixed in 2.3.8 Patch available GHSA-h27v-ph7w-m9fp

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:*2.0.0 to before 2.3.8Vulnerable0xJacky
  • cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:* Versions 2.0.0 to before 2.3.8 Vulnerable ·0xJacky

Remediation

  • Fix · CNA nginx-ui (0xJacky) Fixed in 2.3.8
  • Fix · GHSA-h27v-ph7w-m9fp github.com/0xJacky/Nginx-UI (Go) Fixed in 2.3.8 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-42221
  2. 2026-10-03 Alias added: GHSA-h27v-ph7w-m9fp

References

Exploit 1

Advisory 1

Other 2

  • TI-2026-25478 Nginx UI: Unauthenticated MCP Endpoint Allows Remote Nginx Takeover CVSS 3.1CRITICAL 9.8
  • TI-2026-25472 nginx-ui Backup Restore Allows Tampering with Encrypted Backups CVSS 4.0CRITICAL 9.4
  • TI-2026-22288 Nginx UI: Unauthenticated Backup Download with Encryption Key Disclosure CVSS 3.1CRITICAL 9.8
  • TI-2024-15821 Nginx-UI arbitrary file write through the Import Certificate feature CVSS 3.1CRITICAL 9.8
  • TI-2026-70057 Code injection in Nginx UI backup restore allows code execution CVSS 4.0CRITICAL 9.4
  • TI-2026-32056 Nginx UI: Server-Side Request Forgery (SSRF) via Cluster Proxy Middleware Allows Access to Internal Services CVSS 3.1CRITICAL 9.9
See all 31 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences