Nginx UI: MCP `nginx_config_add` Bypasses Directive Validation — Authenticated RCE

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-84318
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-12 21:17:22 UTC
Updated2026-10-13 15:17:50 UTC
DescriptionNginx 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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

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

Problem Types: CWE-693 | CWE-693 CWE-693: Protection Mechanism Failure

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA 0xJacky Nginx-ui affected >= 2.0.0-rc.6, < 2.4.1 Not specified

References

ReferenceSourceLinkTags
github.com/0xJacky/nginx-ui/security/advisories/GHSA-9jww-cxg5-rj9m 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/0xJacky/nginx-ui/releases/tag/v2.4.1 [email protected] github.com
github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2 [email protected] github.com
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