MCP fetch server exposes SSRF vulnerability CVE-2026-104120, public exploit has appeared and fix PR not merged

The fetch_url function of the Model Context Protocol reference fetch server has a server-side request forgery vulnerability, CVE-2026-104120. The NVD record shows that mcp-server-fetch and mcp-server-everything up to version 2026.6.4 are affected, a public exploit has been disclosed, and the fix PR #4890 remained an unmerged draft as of October 4, 2026. The vulnerability is located in the Fetch Tool component of mcp_server_fetch/server.py, and manipulating the url/path parameters can trigger it. VulDB gives CVSS 3.1 7.3 and CVSS 4.0 5.5, the weakness is CWE-918, and NVD has marked the record as Deferred without independent analysis.