From a6189f0690b5ac27b98da7d8b8ebde0ffe17aa28 Mon Sep 17 00:00:00 2001
From: Jihaochang1 <358550956@qq.com>
Date: Fri, 23 Oct 2026 15:21:11 +0800
Subject: [PATCH] fix: handle HEAD on SSE endpoint to prevent connection leaks
 (fixes #3736)

---
 src/mcp/server/sse.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/mcp/server/sse.py b/src/mcp/server/sse.py
index d71ef25004..ca65e93254 100644
--- a/src/mcp/server/sse.py
+++ b/src/mcp/server/sse.py
@@ -15,6 +15,8 @@
 
     # Define handler functions
     async def handle_sse(request):
+    if scope["method"] == "HEAD":
+        return Response(media_type="text/event-stream", headers={"Cache-Control": "no-store"})
         async with sse.connect_sse(
             request.scope, request.receive, request._send
         ) as streams: