CVE-2026-42222 nginx-ui: Unauthenticated first-boot instance claim via POST /api/install allows remote bootstrap takeover
Unauthenticated attackers can claim the initial installation instance via the install API, gaining administrative control over the Nginx UI.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42222?
CVE-2026-42222 is a high-severity authentication bypass vulnerability in 0xJacky nginx-ui, published on 4 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Nginx UI is a web user interface for the Nginx web server. In version 2.3.5, an unauthenticated bootstrap takeover exists in nginx-ui during the initial installation window exposed by POST /api/install. At time of publication no public patches are available.
Which versions are affected by CVE-2026-42222?
3 open source packages ship an affected version, including github.com/0xJacky/nginx-ui. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/0xJacky/nginx-ui Go | All versions | None |
github.com/0xJacky/nginx-ui Go | All versions | None |
github.com/0xJacky/nginx-ui Go | All versions | None |
Products include Nginxui Nginx Ui.
How do I fix CVE-2026-42222?
No fix published yet.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-42222 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42222 exists.
Other vulnerabilities in 0xJacky nginx-ui
- CVE-2026-33032 Nginx UI: Unauthenticated MCP Endpoint Allows Remote Nginx Takeover
- CVE-2026-27944 Nginx UI: Unauthenticated Backup Download with Encryption Key Disclosure
- CVE-2024-23827 Nginx-UI arbitrary file write through the Import Certificate feature
- CVE-2026-107806 Nginx UI: Authenticated Remote Code Execution via Backup Restore App Config Overwrite
- CVE-2026-33026 nginx-ui Backup Restore Allows Tampering with Encrypted Backups
Sources
Also known as GHSA-mxqh-q9h6-v8pq, GO-2026-5521.