Nginx UI: MCP nginx_config_add skips config directive validation → authenticated nginx directive injection (RCE on the official image)
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-84317
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 17:22 UTC · Revision 1
Source evidence
Nginx UI: MCP nginx_config_add skips config directive validation → authenticated nginx directive injection (RCE on the official image)
core-osv · Original sourcePublished 12 Oct 2026, 20:59 UTC
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.
osv:CVE-2026-84317
Complete source record
{
"id": "1f0dbbe7d61e68e7abfdd1fa3a14f047b24d801d0e73bec5733eeda4dd9a9bbf",
"url": "https://osv.dev/vulnerability/CVE-2026-84317",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Nginx UI: MCP nginx_config_add skips config directive validation → authenticated nginx directive injection (RCE on the official image)",
"summary": "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.",
"evidence": "osv:CVE-2026-84317",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-84317",
"aliases": [
"CVE-2026-84317",
"GHSA-76pm-mq2q-9gcr",
"GO-2026-6779"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/0xjacky/nginx-ui",
"type": "GIT",
"events": [
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{
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{
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}
],
"database_specific": {
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{
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"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
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{
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],
"modified": "2026-10-28T02:30:38.035633257Z",
"provider": "osv",
"references": [
"https://github.com/0xJacky/nginx-ui/releases/tag/v2.4.1",
"https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-76pm-mq2q-9gcr",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84317.json",
"https://nvd.nist.gov/vuln/detail/CVE-2026-84317",
"https://github.com/0xJacky/nginx-ui/commit/23d1934099b05b2a01589b48129dc3d3159d91c2"
],
"provider_metadata": {
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],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84317.json"
}
},
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{
"value": "CVE-2026-84317",
"evidence": "/id"
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],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 505282,
"published_at": "2026-10-12T20:59:58.019+00:00"
}