CVE-2026-42222: nginx-ui: Unauthenticated first-boot instance claim via POST /api/install allows remote bootstrap takeover

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-04 · updated 2026-10-26
Weakness: CWE-284

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.

Affected products

0xJacky nginx-ui: 2.3.5

References

https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-mxqh-q9h6-v8pq
https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-mxqh-q9h6-v8pq

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