A critical Server-Side Request Forgery vulnerability in the FrontMCP framework allows unauthenticated attackers to access internal network resources or read local files.

The vulnerability exists because the library uses a JSON schema parser that does not restrict URL resolutions. An unauthenticated attacker can provide a malicious OpenAPI specification containing crafted $ref pointers to force the server to fetch sensitive internal data or local files.

The ability to perform SSRF and read local files presents a significant risk to organizational infrastructure. An attacker can leverage this flaw to probe internal network services that are otherwise shielded from the internet, potentially leading to the exposure of cloud metadata credentials or sensitive local configuration files. With a CVSS score of 7.5, this high-severity flaw requires immediate attention to prevent unauthorized data exfiltration.

Immediate Action: Update all affected components to the patched versions: mcp-from-openapi to 2.3.0, and both @frontmcp/sdk and @frontmcp/adapters to 1.0.4.

Proactive Monitoring: Inspect server logs for unexpected outbound requests originating from the application server, particularly those targeting internal IP ranges or local file paths.

Compensating Controls: Implement strict egress filtering on the application server to prevent connections to internal network segments or unauthorized external endpoints.

Public Exploit Available: Unknown

Given the capability for unauthenticated attackers to read local files and probe internal networks, this vulnerability poses a clear threat to data confidentiality. Organizations should prioritize updating the FrontMCP framework components to the specified patched versions to neutralize the attack vector. Failure to apply these updates leaves the application susceptible to unauthorized access and internal resource discovery.