Critical severity · published May 4, 2026
CVE-2026-42222
nginx-ui: Unauthenticated first-boot instance claim via POST /api/install allows remote bootstrap takeover
9.8
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NG
nginx-ui · 0xJacky
= 2.3.5 · source: vendor
NU
Nginx UI · Nginxui
2.3.5 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42222
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42222
Exploit
https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-mxqh-q9h6-v8pq
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