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CVE-2026-39885— FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications

Quick assessment

Affected
agentfront frontmcp
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

frontmcp是AgentFront开源的一个基于TypeScript的MCP服务器开发框架。 FrontMCP 2.3.0之前版本存在代码问题漏洞，该漏洞源于未限制URL引用解析，可能导致服务端请求伪造和本地文件读取。

CVSS 7.5 · High EPSS 0.42% · P35
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I. Basic Information for CVE-2026-39885

Vulnerability Information
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Vulnerability Title
FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
frontmcp 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
frontmcp是AgentFront开源的一个基于TypeScript的MCP服务器开发框架。 FrontMCP 2.3.0之前版本存在代码问题漏洞，该漏洞源于未限制URL引用解析，可能导致服务端请求伪造和本地文件读取。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
agentfront frontmcp < 1.0.4 -
@frontmcp adapters < 1.0.4 -
@frontmcp sdk < 1.0.4 -
frontmcp mcp-from-openapi < 2.3.0 -

II. Public POCs for CVE-2026-39885

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8383 chars
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III. Intelligence Information for CVE-2026-39885

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Vendor Advisories for CVE-2026-39885 (1)

IV. Related Vulnerabilities

Same product: frontmcp
Same vendor: agentfront
Same weakness: CWE-918

V. Comments for CVE-2026-39885

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