What’s Vulnerable › Vulnerabilities

CVE-2026-84318: Nginx UI: MCP `nginx_config_add` Bypasses Directive Validation — Authenticated RCE

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-12 · updated 2026-10-13
• Weakness: CWE-693

Description

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 products

• 0xJacky nginx-ui: from 2.0.0-rc.6, < 2.4.1

References

• https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2
• https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1
• https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-9jww-cxg5-rj9m
• https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-9jww-cxg5-rj9m

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