CVE-2026-84318
Nginx UI: MCP `nginx_config_add` Bypasses Directive Validation — Authenticated RCE
Nginx UI is a web user interface for the Nginx web server. From 2.0.0-rc.6 until 2.4.1, the MCP tool nginx_config_add writes nginx configuration files to disk and triggers an nginx reload without calling config.ValidateConfigFile. The identical flow in the REST API (POST /api/configs) does call that function and correctly rejects dangerous directives. An authenticated attacker can exploit this gap to write config files containing any blocked directive (perl, js_import, load_module, user root, etc.), bypassing nginx-ui's entire security layer. On a server with the nginx Perl, njs, or Lua module loaded, this is post-authentication Remote Code Execution. This issue is fixed in version 2.4.1.
- Affected
- 0xJacky · nginx-ui
- CVSS v3.1 GITHUB
- 8.8 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS
- 0.62% chance of exploitation in the next 30 days, 49th percentile
- Published
- 2026-10-12
- Updated
- 2026-10-13