FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications
FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 2.3.0, the mcp-from-openapi library uses @apidevtools/json-schema-ref-parser to dereference $ref pointers in OpenAPI specifications without configuring any URL restrictions or custom resolvers. A malicious OpenAPI specification containing $ref values pointing to internal network addresses, cloud metadata endpoints, or local files will cause the library to fetch those resources during the initialize() call. This enables Server-Side Request Forgery (SSRF) and local file read attacks when processing untrusted OpenAPI specifications. This vulnerability is fixed in 2.3.0.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-39885
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 04:22 UTC · Revision 1
Source evidence
FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications
core-osv · Original sourcePublished 8 Apr 2026, 20:34 UTC
FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 2.3.0, the mcp-from-openapi library uses @apidevtools/json-schema-ref-parser to dereference $ref pointers in OpenAPI specifications without configuring any URL restrictions or custom resolvers. A malicious OpenAPI specification containing $ref values pointing to internal network addresses, cloud metadata endpoints, or local files will cause the library to fetch those resources during the initialize() call. This enables Server-Side Request Forgery (SSRF) and local file read attacks when processing untrusted OpenAPI specifications. This vulnerability is fixed in 2.3.0.
osv:CVE-2026-39885
Complete source record
{
"id": "646c190101e6d167a691a7fe47144d243ec93f09a9687510ce7176f377535bcf",
"url": "https://osv.dev/vulnerability/CVE-2026-39885",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications",
"summary": "FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 2.3.0, the mcp-from-openapi library uses @apidevtools/json-schema-ref-parser to dereference $ref pointers in OpenAPI specifications without configuring any URL restrictions or custom resolvers. A malicious OpenAPI specification containing $ref values pointing to internal network addresses, cloud metadata endpoints, or local files will cause the library to fetch those resources during the initialize() call. This enables Server-Side Request Forgery (SSRF) and local file read attacks when processing untrusted OpenAPI specifications. This vulnerability is fixed in 2.3.0.",
"evidence": "osv:CVE-2026-39885",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-39885",
"aliases": [
"CVE-2026-39885",
"GHSA-v6ph-xcq9-qxxj"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/agentfront/frontmcp",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "c13e7651968d08223bcf996d4d39f84fe2040c4c"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "1.0.4"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "c13e7651968d08223bcf996d4d39f84fe2040c4c"
}
],
"source": "REFERENCES_TAG",
"original_tag": "v1.0.4"
},
{
"cpe": "cpe:2.3:a:agentfront:\\@frontmcp\\/adapters:*:*:*:*:*:node.js:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "1.0.4"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:agentfront:\\@frontmcp\\/sdk:*:*:*:*:*:node.js:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "1.0.4"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:agentfront:frontmcp:*:*:*:*:*:node.js:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "1.0.4"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v1.0.3",
"v1.0.2",
"v1.0.1",
"v1.0.0",
"v1.0.0-rc.1",
"v1.0.0-beta.14",
"v1.0.0-beta.13",
"v1.0.0-beta.12",
"v1.0.0-beta.11",
"v1.0.0-beta.10",
"v1.0.0-beta.9",
"v1.0.0-beta.8",
"v1.0.0-beta.7",
"v1.0.0-beta.6",
"v1.0.0-beta.5",
"v1.0.0-beta.4",
"v1.0.0-beta.3",
"v1.0.0-beta.2",
"v1.0.0-beta.1",
"v0.8.1",
"v0.8.0",
"v0.7.2",
"v0.7.1",
"v0.6.3",
"v0.6.2",
"v0.6.1",
"v0.6.0",
"v0.5.1",
"v0.5.0",
"v0.4.0",
"v0.3.1",
"v0.3.0",
"v0.2.5"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39885.json"
}
}
],
"modified": "2026-10-28T02:30:25.787952358Z",
"provider": "osv",
"references": [
"https://github.com/agentfront/frontmcp/releases/tag/v1.0.4",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39885.json",
"https://github.com/agentfront/frontmcp/security/advisories/GHSA-v6ph-xcq9-qxxj",
"https://nvd.nist.gov/vuln/detail/CVE-2026-39885"
],
"provider_metadata": {
"cwe_ids": [
"CWE-918"
],
"cna_assigner": "GitHub_M",
"unresolved_ranges": [
{
"extracted_events": [
{
"range": [
{
"fixed": "2.3.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
}
]
}
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39885.json"
}
},
"related_cves": [
{
"value": "CVE-2026-39885",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 492440,
"published_at": "2026-04-08T20:34:20.538+00:00"
}