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Vulnerability · Published Oct 12, 2026 · Assigned by GitHub_M

CVE-2026-84317Nginx UI: MCP nginx_config_add skips config directive validation → authenticated nginx directive injection (RCE on the official image)

High 8.8

In plain English

A high-severity improper input validation in nginx-ui from 0xJacky. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.5%top 58.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1, internal/config/validation.go (ValidateConfigFile) is a security control that blocks dangerous nginx directives — js_*, perl_*, load_module of the njs/perl modules, and user root. It is enforced on three of the four config-write paths: api/config/add.go, api/config/modify.go, and mcp/config/config_modify.go. The fourth path — the MCP tool nginx_config_add (mcp/config/config_add.go) — does NOT call it: it writes the caller-supplied content straight to disk and reloads nginx. An authenticated MCP caller (or an MCP agent induced via prompt injection) can therefore inject exactly the directives the control is meant to block, leading to nginx code execution on deployments where the njs/perl module is available (e.g. the official Docker image). This issue is fixed in version 2.4.1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/0xJacky/Nginx-UI1.9.10-0.20260703131214-23d1934099b0GHSA-76pm-mq2q-9gcr
Gogithub.com/0xJacky/Nginx-UI1.9.10-0.20260703131214-23d1934099b0GO-2026-6779

Affected products (as reported)

VendorProductVersions
0xJacky nginx-ui < 2.4.1

Weakness: CWE-20, CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References