Nginx-UI: Unauthenticated first-boot instance claim via POST /api/install allows remote bootstrap takeover

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-42222: 0.34% estimated exploitation activity in the next 30 days; percentile 27.45 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary An unauthenticated bootstrap takeover exists in nginx-ui during the initial installation window exposed by POST /api/install. When the instance is still uninitialized, POST /api/install is reachable without authentication and accepts attacker-controlled bootstrap data. The handler sets the application's JWT secret, the node secret, the certificate email, and the initial administrator username and password. This allows an attacker who can reach a fresh instance during the initial 10-minute setup window to claim the installation before the legitimate operator. This is not a general post-install takeover. The exposure condition is narrower: the target must still be in its first-run state and still be within the initial setup window. In practice, this makes the issue most relevant during initial deployment, rebuilds, ephemeral test environments, LAN-accessible fresh installs, or temporarily exposed setup workflows. The primary attack path is direct network access to a reachable…

Published by the source

6 May 2026, 16:59 UTC

Last modified by the source

6 May 2026, 16:59 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mxqh-q9h6-v8pq

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# Patch Next advisory brief: CVE-2026-42222

Advisory: Nginx-UI: Unauthenticated first-boot instance claim via POST /api/install allows remote bootstrap takeover
IDs: CVE-2026-42222, GHSA-mxqh-q9h6-v8pq
Record: https://patchnext.com/advisories/cve-2026-42222 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/0xJacky/nginx-ui: affected >= 2.3.5, <= 2.3.5

## Suggested inspection (read-only)
- Go github.com/0xJacky/nginx-ui: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/0xJacky/nginx-ui.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mxqh-q9h6-v8pq (GitHub-reviewed advisory GHSA-mxqh-q9h6-v8pq lists affected ranges: Go github.com/0xJacky/nginx-ui >=2.3.5 <=2.3.5)

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