Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating tool results against output schemas

影響: pip:mcp >= 2.0.0, < 2.2.0 → 2.2.0, pip:mcp >= 1.10.0, < 1.30.0 → 1.30.0

In affected versions, when a connected MCP server declared an outputSchema for a tool, the SDK's client validated each call_tool result with jsonschema's default resolver, which fetches any $ref it cannot resolve locally by opening the URL. A server could therefore put an http://, https:// or file:// reference in a tool's output schema and make the client: - request that URL, or read that local file, from the client's own network position on every call of the tool (the content was used only as…

在 GitHub Advisory Database 阅读

2026/10/28 06:05，GitHub Advisory Database 发布了“Model Context Protocol Python SDK: Client fetched server-chosen $ref URLs while validating tool results against output schemas”（类型：漏洞公告）。严重程度为“中危”（medium）。相关技术：Python。CVE：CVE-2026-116686。