# CVE-2026-84317: Nginx UI: MCP nginx_config_add skips config directive validation → authenticated nginx directive injection (RCE on the official image)

> Authenticated attackers can inject dangerous Nginx directives via the MCP config add tool, leading to remote code execution on systems with njs or perl modules.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Oct 2026
- **Updated:** 13 Oct 2026
- **Also known as:** GHSA-76pm-mq2q-9gcr, GO-2026-6779

## What is CVE-2026-84317?

CVE-2026-84317 is a high-severity code injection vulnerability in 0xJacky nginx-ui, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.1, internal/config/validation.go (ValidateConfigFile) is a security control that blocks dangerous nginx directives — js_*, perl_*, load_module of the njs/perl modules, and user root. It is enforced on three of the four config-write paths: api/config/add.go, api/config/modify.go, and mcp/config/config_modify.go. The fourth path — the MCP tool nginx_config_add (mcp/config/config_add.go) — does NOT call it: it writes the caller-supplied content straight to disk and reloads nginx. An authenticated MCP caller (or an MCP agent induced via prompt injection) can therefore inject exactly the directives the control is meant to block, leading to nginx code execution on deployments where the njs/perl module is available (e.g. the official Docker image). This issue is fixed in version 2.4.1.

Weakness: CWE-693 (Protection Mechanism Failure), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-84317?

3 open source packages ship an affected version, including github.com/0xJacky/Nginx-UI.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/0xJacky/Nginx-UI` | Go | All versions | 1.9.10-0.20260703131214-23d1934099b0 |
| `github.com/0xJacky/Nginx-UI` | Go | All versions | 1.9.10-0.20260703131214-23d1934099b0 |
| `github.com/0xJacky/Nginx-UI` | Go | All versions | 1.9.10-0.20260703131214-23d1934099b0 |

## How do I fix CVE-2026-84317?

Upgrade github.com/0xJacky/Nginx-UI to 1.9.10-0.20260703131214-23d1934099b0 or later.

## Is CVE-2026-84317 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84317 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84317 and fix it if it is affected.

What it is: CVE-2026-84317 is a high-severity code injection vulnerability in 0xJacky nginx-ui, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-84317 exists.

Affected packages and fixed versions:
- github.com/0xJacky/Nginx-UI (Go): affected all versions; fixed in 1.9.10-0.20260703131214-23d1934099b0
- github.com/0xJacky/Nginx-UI (Go): affected all versions; fixed in 1.9.10-0.20260703131214-23d1934099b0
- github.com/0xJacky/Nginx-UI (Go): affected all versions; fixed in 1.9.10-0.20260703131214-23d1934099b0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84317/ (Markdown: https://insights.sbomify.com/CVE-2026-84317/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84317
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84317
- OSV: https://osv.dev/vulnerability/CVE-2026-84317

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84317/
Summaries are generated and may contain mistakes; the official description above is the record.