LangChain is a framework for building agents and LLM-powered applications. Prior to versions 0.3.81 and 1.2.5, a serialization injection vulnerability exists in LangChains dumps() and dumpd() functions. The functions do not escape dictionaries with lc keys when serializing free-form dictionaries. The lc key is used internally by LangChain to mark serialized objects. When user-controlled data contains this key structure, it is treated as a legitimate LangChain object during deserialization rather than plain user data. This issue has been patched in versions 0.3.81 and 1.2.5.
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.