Affected: langchain-ai langgraph

LangGraph SQLite Checkpoint is an implementation of LangGraph CheckpointSaver that uses SQLite DB (both sync and async, via aiosqlite). In versions 2.1.2 and below, the JsonPlusSerializer (used as the default serialization protocol for all checkpointing) contains a Remote Code Execution (RCE) vulnerability when deserializing payloads saved in the "json" serialization mode. By default, the serializer attempts to use "msgpack" for serialization. However, prior to version 3.0 of the checkpointer library, if illegal Unicode surrogate values caused serialization to fail, it would fall back to using the "json" mode. This issue is fixed in version 3.0.0.

Affected: PyPI: langgraph-checkpoint

# Summary

Prior to `langgraph-checkpoint` version `3.0` , LangGraph’s `JsonPlusSerializer` (used as the default serialization protocol for all checkpointing) contains a remote code execution (RCE) vulnerability when deserializing payloads saved in the `"json"` serialization mode.

If an attacker can cause your application to persist a payload serialized in this mode, they may be able to also send malicious content that executes arbitrary Python code during deserialization.

Upgrading to version langgraph-checkpoint `3.0` patches this vulnerability by preventing deserialization of custom objects saved in this mode.

If you are deploying in `langgraph-api`, any version `0.5` or later is also free of this vulnerability.

# Details

**Affected file / component**

[jsonplus.py](https://github.com/langchain-ai/langgraph/blob/c5744f583b11745cd406f3059903e17bbcdcc8ac/libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py)

By default, the serializer attempts to use `"msgpack"` for serialization. However, prior to version `3.0` of the checkpointer library, if illegal Unicode surrogate values caused serialization to fail, it would fall back to using the `"json"` mode.

When operating in this mode, the deserializer supports a constructor-style format (`lc == 2`, `type == "constructor"`) for custom objects to allow them to be reconstructed at load time. If an attacker is able to trigger this mode with a malicious payload, deserializing allow the attacker to execute arbitrary functi…