CVSS 8.1 · HIGH

CVE-2026-42222

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.

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Analysis

Nginx UI is a popular open-source management interface for Nginx servers. This vulnerability allows an unauthenticated attacker to take over the application during the installation phase, leading to full control over Nginx configurations. High severity and realistic exploit scenario for anyone deploying new instances.

Severity

Score: 8.1(HIGH)

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

AV: NETWORK

AC: HIGH

PR: NONE

UI: NONE

S: UNCHANGED

C: HIGH

I: HIGH

A: HIGH

Weakness (CWE): CWE-284CWE-306

EPSS

Probability of exploitation (next 30 days): 0.0004 (0.0%)

Percentile: 12.4%

EPSS: 2026-05-06

Affects

nginxui:nginx_ui

Technical description

Published: 5/4/2026, 9:16:32 PM

Last modified: 5/6/2026, 5:47:59 PM

References

How to read this card

Actively exploited

KEV (Known Exploited Vulnerabilities) is CISA's catalog of CVEs confirmed as actively exploited in the real world. If a CVE is on KEV, someone is already using it in attacks.

CVSS 10.0

CVSS 10.0 — máxima severidad teórica. Explotable de forma remota, sin privilegios, con impacto total. Aún no confirmada como explotada en el mundo real, pero parchea ya.

AI-recommended

Un modelo de lenguaje revisó el CVE y consideró que afecta a software ampliamente desplegado o herramientas comunes de desarrollo. Un humano del equipo aprobó la publicación antes de que llegara aquí.

Categorías de impacto que evalúa la IA

widely_deployed_infra — kernel Linux, OpenSSL, glibc, k8s, Docker, nginx, OpenSSH.

popular_dev_tooling — Node.js, Python, Go, React, Next.js, librerías comunes de npm/pip.

common_consumer_software — Chrome, Firefox, Windows, macOS, apps móviles populares.

enterprise_saas — GitHub, GitLab, Atlassian, Salesforce, Cisco, Fortinet, Ivanti.

niche_software — CMS regionales, herramientas de hobby, librerías de poco uso.

not_relevant — firmware específico de proveedor, software descontinuado.

EPSS — EPSS (Exploit Prediction Scoring System) by FIRST.org estimates the probability that a CVE will be exploited in the next 30 days. Range is 0 to 1; very fresh CVEs typically score low until evidence accumulates.