CVE-2026-84318: high-severity vulnerability in 0xJacky nginx-ui
Nginx UI: MCP `nginx_config_add` Bypasses Directive Validation — Authenticated RCE
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.8epss 0.8%
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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products
0xJacky · nginx-uiRelated CVEs — 0xJacky nginx-ui
In the same product, most dangerous first.
CVE-2026-33032CRITICALNginx UI: Unauthenticated MCP Endpoint Allows Remote Nginx TakeoverEPSS 35.3%CVE-2024-49368HIGHUnchecked logrotate settings lead to arbitrary command executionEPSS 27.7%CVE-2026-27944CRITICALNginx UI: Unauthenticated Backup Download with Encryption Key DisclosureEPSS 22.8%CVE-2024-22198HIGHAuthenticated (user role) arbitrary command execution by modifying `start_cmd` setting (GHSL-2023-268)EPSS 4.1%CVE-2024-22197HIGHAuthenticated (user role) remote command execution by modifying `nginx` settings (GHSL-2023-269)EPSS 1.5%CVE-2026-42221HIGHnginx-ui: Unauthenticated First-Run Installer Allows Remote Initial Admin ClaimEPSS 1.3%