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Title: fix: reject changed duplicate initialize by he-yufeng · Pull Request #2606 · modelcontextprotocol/python-sdk · GitHub

Open Graph Title: fix: reject changed duplicate initialize by he-yufeng · Pull Request #2606 · modelcontextprotocol/python-sdk

X Title: fix: reject changed duplicate initialize by he-yufeng · Pull Request #2606 · modelcontextprotocol/python-sdk

Description: Summary reject a second initialize request if it tries to change the session's client parameters keep the first client_params intact so later capability checks cannot be spoofed by a duplicate handshake add a regression test covering the changed-params path To verify uv run pytest tests/server/test_session.py -q -k "duplicate_initialize or server_session_initialize" uv run ruff check src/mcp/server/session.py tests/server/test_session.py uv run pyright src/mcp/server/session.py tests/server/test_session.py uv run python -m py_compile src/mcp/server/session.py tests/server/test_session.py git diff --check Closes #2605

Open Graph Description: Summary reject a second initialize request if it tries to change the session's client parameters keep the first client_params intact so later capability checks cannot be spoofed by a duplicate...

X Description: Summary reject a second initialize request if it tries to change the session's client parameters keep the first client_params intact so later capability checks cannot be spoofed by a dupli...

Opengraph URL: https://github.com/modelcontextprotocol/python-sdk/pull/2606

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74ae395 fix: reject changed duplicate initialize he-yufeng May 15, 2026 https://github.com/modelcontextprotocol/python-sdk/pull/2606/commits/74ae39529f48e3f96a4a6311c86e6a3e0607bed1
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