CVE-2025-68664

The dumps() and dumpd() functions used for data serialization do not filter dictionaries containing the 'lc' key, which is internally reserved by LangChain to mark serialized objects. If user-controlled data contains such a key structure, it is treated during deserialization as a valid LangChain object rather than plain user data. This results in untrusted data being processed by the framework's deserialization mechanisms (CWE-502: Deserialization of Untrusted Data).

An attacker can provide crafted data that, after deserialization, will be treated as legitimate LangChain objects, which may lead to disclosure of sensitive information and limited modification of the application state. The vulnerability has a scope exceeding the original component (S:C), which increases the potential impact on the environment.

LangChain Core should be updated to version 0.3.81 or 1.2.5 (or newer). Patches are available in the LangChain project GitHub repository (commits 5ec0fa69 and d9ec4c5c). Until updating, avoid passing untrusted user data directly to the dumps() and dumpd() functions.

LangChain Core in versions before 0.3.81 and before 1.2.5