CVE-2026-34237

描述

### Summary **Hardcoded Wildcard CORS (Access-Control-Allow-Origin: * )** - https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289 - https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525 ### Attack Scenario An attacker-controlled web page instructs the victim's browser to open GET https://internal-mcp-server/sse. Because Access-Control-Allow-Origin: * allows cross-origin SSE reads, the attacker's page receives the endpoint event — which contains the session ID. The attacker can then POST to that endpoint from their page using the victim's browser as a relay. ### Comparison with python-sdk No Access-Control-Allow-Origin header is emitted by either Python transport. The browser's default same-origin policy remains in full effect. https://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/sse.py https://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/streamable_http.py ### Recommendation In the SDK, the transport layer should not own CORS policy. Server implementors who need cross-origin access can add a CORS filter at the servlet filter or Spring Security layer. ### Reference - https://cheatsheetseries.owasp.org/cheatsheets/HTTP_Headers_Cheat_Sheet.html#access-control-allow-origin

如何修補 CVE-2026-34237

要修補 CVE-2026-34237,請將受影響套件升級到下列已修補版本。

• —升級至 1.0.1 或更新版本

CVE-2026-34237 正在被利用嗎?

低 — EPSS 為 0.0%,目前沒有觀察到大規模利用活動。

受影響套件(1)

• from 0, < 1.0.1