fix: patch CVE-2026-26220

[lucrbvi]

This pull request aims to fix the CVE-2026-26220 vulnerability (score of 9.3) by replacing pickle with json when using websockets.

The PR focus on replacing pickle but it is recommended to add an authentication layer with secrets when using websockets to prevent bad actors to send malicious data.

I have also replaced the use of pickle in lightllm/distributed/pynccl.py when we send and receive data from the torch TCPStore. I would like feedback on this change.

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Summary of Changes

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This pull request addresses a critical security vulnerability by systematically replacing the pickle serialization module with ujson wherever data is transmitted or received, particularly over websockets and within the torch TCPStore communication. The change aims to prevent malicious code execution through deserialization, thereby significantly improving the application's security. It also standardizes the serialization mechanism, contributing to more robust and maintainable code.

Highlights

• Security Vulnerability Fix (CVE-2026-26220): Replaced the insecure pickle serialization module with ujson across various components to mitigate CVE-2026-26220, which had a high severity score of 9.3. This change enhances the security posture of the application by preventing potential deserialization attacks.
• Serialization Standardisation: Standardized data serialization to ujson for inter-process communication, including websocket messages and data exchange via torch TCPStore, ensuring consistent and safer data handling throughout the system.
• Improved Data Handling: Updated data encoding and decoding logic to correctly handle ujson's string output and byte input requirements, ensuring seamless transition from pickle's byte-oriented serialization.

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Changelog

• lightllm/distributed/pynccl.py
  • Imported ujson for JSON serialization.
  • Replaced pickle.dumps(obj) with json.dumps(obj).encode() when sending objects.
  • Replaced pickle.loads(data) with json.loads(data.decode()) when receiving objects.
• lightllm/server/api_http.py
  • Replaced pickle.loads(data) with json.loads(data.decode()) for deserializing websocket messages in register_and_keep_alive.
  • Replaced pickle.loads(data) with json.loads(data.decode()) for deserializing upkv_status in kv_move_status.
• lightllm/server/config_server/api_http.py
  • Imported ujson for JSON serialization.
  • Replaced pickle.loads(await websocket.receive_bytes()) with json.loads(await websocket.receive_bytes().decode()) for registered objects.
  • Replaced pickle.dumps(registered_pd_master_objs) with json.dumps(registered_pd_master_objs).encode() for serializing registered objects.
• lightllm/server/httpserver/manager.py
  • Imported ujson for JSON serialization.
  • Replaced pickle.dumps(...) with json.dumps(...).encode() for sending NIXL_UPLOAD_NP_PROMPT_IDS.
  • Replaced pickle.dumps(decode_node_info) with json.dumps(decode_node_info).encode() for setting nixl_params.
• lightllm/server/httpserver/pd_loop.py
  • Replaced pickle.loads(recv_bytes) with json.loads(recv_bytes.decode()) for deserializing received objects.
  • Replaced pickle.loads(base64.b64decode(base64data)) with json.loads(base64.b64decode(base64data.decode())) for deserializing pd_master_obj.
  • Replaced pickle.dumps(...) with json.dumps(...).encode() for sending TOKEN_PACKS.
• lightllm/server/httpserver_for_pd_master/manager.py
  • Replaced pickle.dumps(...) with json.dumps(...).encode() for sending ObjType.REQ messages.
  • Replaced pickle.dumps(...) with json.dumps(...).encode() for sending ObjType.ABORT messages.
  • Replaced pickle.loads(nixl_params) with json.loads(nixl_params.decode()) for deserializing decode_node_info.
• lightllm/server/httpserver_for_pd_master/register_loop.py
  • Removed pickle import and imported ujson for JSON serialization.
  • Replaced pickle.dumps(pd_master_obj) with json.dumps(pd_master_obj).encode() for sending registration objects.
• lightllm/server/router/model_infer/infer_batch.py
  • Removed pickle import and imported ujson for JSON serialization.
  • Replaced pickle.loads(self.shm_param.nixl_params.get()) with json.loads(self.shm_param.nixl_params.get().decode()) for nixl_decode_node.
• lightllm/server/router/model_infer/mode_backend/continues_batch/pd_mode/decode_node_impl/up_status.py
  • Replaced json import with ujson as json for JSON serialization.
  • Replaced pickle.dumps(upkv_status) with json.dumps(upkv_status).encode() for sending status updates.
• lightllm/server/router/model_infer/mode_backend/pd_nixl/decode_node_impl/decode_trans_process.py
  • Removed pickle import and imported ujson for JSON serialization.
  • Replaced pickle.dumps(decode_node_info) with json.dumps(decode_node_info).encode() for nixl_params.
  • Replaced pickle.loads(notify) with json.loads(notify.decode()) for deserializing notifications.
  • Replaced pickle.dumps(remote_trans_task.createRetObj()) with json.dumps(remote_trans_task.createRetObj()).encode() for sending notifications.
• lightllm/server/router/model_infer/mode_backend/pd_nixl/decode_node_impl/up_status.py
  • Replaced pickle.dumps(upkv_status) with json.dumps(upkv_status).encode() for sending status updates.
• lightllm/server/router/model_infer/mode_backend/pd_nixl/nixl_kv_transporter.py
  • Imported ujson for JSON serialization.
  • Replaced pickle.dumps(new_trans_task) with json.dumps(new_trans_task).encode() for sending notifications.
  • Replaced pickle.dumps(notify_obj) with json.dumps(notify_obj).encode() for make_prepped_xfer.
• lightllm/server/router/model_infer/mode_backend/pd_nixl/prefill_node_impl/prefill_trans_process.py
  • Removed pickle import and imported ujson for JSON serialization.
  • Replaced pickle.loads(notify) with json.loads(notify) for deserializing notifications.

Activity

• The pull request was created by lucrbvi to address CVE-2026-26220 by replacing pickle with json for serialization.

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Code Review

This pull request replaces pickle with json for data serialization, which is a great security improvement. The changes are widespread across the codebase, touching websocket communication, TCPStore, and inter-process communication. The overall direction is correct.

However, I've found a few critical bugs where the new json deserialization code is incorrect and would lead to runtime errors. These are mainly due to incorrect handling of bytes vs str and incorrect await syntax.

Please address the critical issues to ensure the application runs correctly after these changes.