{"id":"GHSA-vc32-4gwf-77xp","summary":"Nginx UI: OTP secure-session step-up can be bypassed via MCP configuration tools","details":"### Summary\nAn OTP-enabled authenticated user who cannot use the HTTP configuration mutation endpoints without a valid secure session can still mutate Nginx configuration through `/mcp` and `/mcp_message` using only ordinary authentication.\n\n### Details\nThe HTTP configuration mutation surface is explicitly grouped behind `middleware.RequireSecureSession()`. By contrast, the MCP endpoints are exposed with only `middleware.AuthRequired()`. The MCP server exposes configuration mutation tools including `nginx_config_add` and `nginx_config_modify`, so OTP-enabled users gain an alternate path around the intended step-up requirement.\n\nRelevant code paths:\n- [api/config/router.go](/home/kali/Desktop/bounty/nginx-ui/api/config/router.go:14)\n- [internal/middleware/secure_session.go](/home/kali/Desktop/bounty/nginx-ui/internal/middleware/secure_session.go:52)\n- [mcp/router.go](/home/kali/Desktop/bounty/nginx-ui/mcp/router.go:9)\n- [mcp/config/config_add.go](/home/kali/Desktop/bounty/nginx-ui/mcp/config/config_add.go:34)\n- [mcp/config/config_modify.go](/home/kali/Desktop/bounty/nginx-ui/mcp/config/config_modify.go:55)\n\nThis is a security-control bypass rather than a missing feature. The product already established that OTP-enabled users should complete a secure session before high-impact configuration mutations are accepted on the HTTP path.\n\n### PoC\nI verified this locally in an isolated environment with a temporary end-to-end harness that exercised the real `/mcp` and `/mcp_message` routes.\n\nWhat the executed test did:\n1. Created a temporary config directory and configured Nginx control commands to harmless local values (`true`) to avoid touching the host.\n2. Created a real OTP-enabled user in a temporary SQLite database.\n3. Generated a real JWT for that OTP-enabled user.\n4. Started a local test server exposing the real `/mcp` and `/mcp_message` routes.\n5. Opened an authenticated SSE connection to `/mcp` with the JWT and no `X-Secure-Session-ID`.\n6. Initialized the MCP session over `/mcp_message`.\n7. Called the real `nginx_config_add` tool over `/mcp_message`.\n8. Verified that the tool succeeded and created `mcp-bypass.conf` in the managed config directory without any secure-session step-up.\n\nObserved result from the actual local verification:\n- The MCP session initialized successfully without any `X-Secure-Session-ID`.\n- The config file was written through the MCP tool path using only JWT authentication.\n\n### Impact\nOTP-enabled accounts lose the intended step-up protection for high-impact Nginx configuration changes when MCP is enabled. A user who should be blocked until re-authenticating can still create or modify configuration files and trigger reload behavior through MCP.","aliases":["CVE-2026-84360"],"modified":"2026-10-15T20:30:03.594105571Z","published":"2026-10-15T20:14:10Z","database_specific":{"github_reviewed_at":"2026-10-15T20:14:10Z","nvd_published_at":"2026-10-12T21:17:22Z","cwe_ids":["CWE-288"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-vc32-4gwf-77xp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84360"},{"type":"WEB","url":"https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2"},{"type":"PACKAGE","url":"https://github.com/0xJacky/nginx-ui"},{"type":"WEB","url":"https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1"}],"affected":[{"package":{"name":"github.com/0xJacky/Nginx-UI","ecosystem":"Go","purl":"pkg:golang/github.com/0xJacky/Nginx-UI"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.9.10-0.20260703131214-23d1934099b0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-vc32-4gwf-77xp/GHSA-vc32-4gwf-77xp.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H"}]}