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CVE-2026-39885

FrontMCP Affected by SSRF via $ref Dereferencing in Untrusted OpenAPI Specifications

Published: Apr 8, 2026Updated: Apr 15, 2026 Sources: CVE List NVDCWE-918
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.3%
Top 77.2%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None
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Weaknesses

CWE-918

Affected Products

\@frontmcp\/adaptersagentfront
Mixed
Security Products / secure-gateway-vpn
\@frontmcp\/sdkagentfront
Mixed
Security Products / secure-gateway-vpn
frontmcpagentfront
Mixed
Security Products / secure-gateway-vpn
mcp-from-openapifrontmcpCloud & SaaS / api-gateway
adapters@frontmcp
agentfrontcommercialSecurity Productsaka agent front, @frontmcp
frontmcpCloud & SaaSaka mcp-from-openapi
and 1 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Command and Control
Initial Access
View detailed technique mapping

References

https://github.com/agentfront/frontmcp/releases/tag/v1.0.4
github.com
https://github.com/agentfront/frontmcp/security/advisories/GHSA-v6ph-xcq9-qxxj
github.com

Timeline

Published
Apr 8, 2026
Last Updated
Apr 15, 2026

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