feat(fetch): add SSRF protection and comprehensive security test suite #3180
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This PR adds Server-Side Request Forgery (SSRF) protection and a comprehensive security test suite to the fetch MCP server. - URL scheme validation (only http/https allowed) - Private IP range blocking (10.x, 172.16-31.x, 192.168.x, 127.x, etc.) - IPv6 private address blocking (::1, fe80::, fc00::, etc.) - Dangerous hostname blocking (localhost, metadata services, etc.) - DNS resolution validation to prevent DNS rebinding - Configurable via MCP_FETCH_ALLOW_PRIVATE_IPS env var - Whitelist support via MCP_FETCH_ALLOWED_PRIVATE_HOSTS - Configurable SSL verification via MCP_FETCH_SSL_VERIFY env var - Comprehensive SSL error handling with helpful messages - SSRF protection tests - Private IP blocking tests - Input validation tests - URL scheme validation tests - Integration tests - Edge case tests ```bash export MCP_FETCH_SSL_VERIFY=false export MCP_FETCH_ALLOW_PRIVATE_IPS=true export MCP_FETCH_ALLOWED_PRIVATE_HOSTS=internal.company.com,api.local ``` fix: address security review feedback - Disable follow_redirects to prevent SSRF bypass via open redirects - Add explicit IP obfuscation detection (decimal/octal/hex formats) - Fix SSL parsing to be fail-secure (only 'false' disables verification) - Clean up test headers (remove enterprise roleplay language) - Add comprehensive tests for IP obfuscation parsing fix: add octal integer IP parsing and fix test naming - Add octal integer format parsing (017700000001 = 127.0.0.1) - Rename SSL test to reflect fail-secure behavior (stays_enabled, not defaults_to_false) - Add tests for octal integer IP obfuscation
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Summary
This PR adds Server-Side Request Forgery (SSRF) protection and a comprehensive security test suite to the fetch MCP server.
Security Features Added
SSRF Protection
SSL Configuration
Test Suite (71 tests)
Configuration
Server Details
Motivation and Context
The fetch server can be exploited for SSRF attacks, allowing malicious actors to access internal services (cloud metadata endpoints, internal APIs, etc.). This PR adds comprehensive protection while maintaining flexibility for legitimate internal use cases through configuration options.
How Has This Been Tested?
Breaking Changes
None. All protections are backward compatible. Private IPs can be enabled via env var if needed.
Types of changes
Checklist
Additional context
This PR builds on #3179 which adds SSL verification configuration.