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HIGH severity

CVE-2026-84360 — Nginx-UI

HIGHFix: 0xJacky/nginx-ui@23d1934

CVE-2026-84360 is a high-severity (CVSS 8.1) CWE-288 vulnerability in github.com/0xJacky/Nginx-UI. A fix is available for github.com/0xJacky/Nginx-UI — see the affected versions and patch details below.

Nginx UI: OTP secure-session step-up can be bypassed via MCP configuration tools

Also known asGHSA-vc32-4gwf-77xpGO-2026-6799
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-84360.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-84360 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,415 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐹github.com/0xJacky/Nginx-UI

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

An 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.

Details

The 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.

Relevant code paths:

This 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.

PoC

I verified this locally in an isolated environment with a temporary end-to-end harness that exercised the real /mcp and /mcp_message routes.

What the executed test did:

  1. Created a temporary config directory and configured Nginx control commands to harmless local values (true) to avoid touching the host.
  2. Created a real OTP-enabled user in a temporary SQLite database.
  3. Generated a real JWT for that OTP-enabled user.
  4. Started a local test server exposing the real /mcp and /mcp_message routes.
  5. Opened an authenticated SSE connection to /mcp with the JWT and no X-Secure-Session-ID.
  6. Initialized the MCP session over /mcp_message.
  7. Called the real nginx_config_add tool over /mcp_message.
  8. Verified that the tool succeeded and created mcp-bypass.conf in the managed config directory without any secure-session step-up.

Observed result from the actual local verification:

  • The MCP session initialized successfully without any X-Secure-Session-ID.
  • The config file was written through the MCP tool path using only JWT authentication.

Impact

OTP-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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/0xJacky/Nginx-UIall versions1.9.10-0.20260703131214-23d1934099b0go get github.com/0xJacky/Nginx-UI@v1.9.10-0.20260703131214-23d1934099b0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/0xJacky/Nginx-UI, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/0xJacky/Nginx-UI to 1.9.10-0.20260703131214-23d1934099b0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-84360 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Summary An 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. ### Details The 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
O3 Security · Impact-Aware SCA

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CVE-2026-84360: Nginx-UI — Fix Available