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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-84317: 0.48% estimated exploitation activity in the next 30 days; percentile 41.29 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary internal/config/validation.go (ValidateConfigFile) is a security control that blocks dangerous nginx directives — js, perl, loadmodule 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/configmodify.go. The fourth path — the MCP tool nginxconfigadd (mcp/config/configadd.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). Root cause — an incomplete hardening patch Commit 3e411d38 ("Harden config write paths", 2026-04-21) introduced ValidateConfigFile and wired it into the config-write paths — but its changeset touched only: api/config/add.go (+6), api/config/modify.go…

Published by the source

15 Oct 2026, 20:11 UTC

Last modified by the source

19 Oct 2026, 21:31 UTC

Source last checked

26 Oct 2026, 15:32 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-76pm-mq2q-9gcr

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6779

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-76pm-mq2q-9gcr

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# Patch Next advisory brief: CVE-2026-84317

Advisory: Nginx UI: MCP nginx_config_add skips config directive validation → authenticated nginx directive injection (RCE on the official image)
IDs: CVE-2026-84317, GHSA-76pm-mq2q-9gcr
Record: https://patchnext.com/advisories/cve-2026-84317 (revision 3, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/0xJacky/Nginx-UI 1.9.10-0.20260703131214-23d1934099b0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/0xJacky/Nginx-UI: affected < 1.9.10-0.20260703131214-23d1934099b0; fixed in 1.9.10-0.20260703131214-23d1934099b0

## Suggested inspection (read-only)
- Go github.com/0xJacky/Nginx-UI: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/0xJacky/Nginx-UI.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6779 (OSV record GO-2026-6779 lists affected ranges: Go github.com/0xJacky/Nginx-UI >=0 <1.9.10-0.20260703131214-23d1934099b0 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-76pm-mq2q-9gcr (OSV record GHSA-76pm-mq2q-9gcr lists affected ranges: Go github.com/0xJacky/Nginx-UI >=0 <1.9.10-0.20260703131214-23d1934099b0 (fixed))
- Verified: https://github.com/advisories/GHSA-76pm-mq2q-9gcr (GitHub-reviewed advisory GHSA-76pm-mq2q-9gcr lists affected ranges: Go github.com/0xJacky/Nginx-UI >=0 <1.9.10-0.20260703131214-23d1934099b0)

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