CVE-2026-44843

Affected versions of the langchain-core package are vulnerable to Unsafe Deserialisation due to runtime code paths that call load() with allowed_objects="all", permitting any trusted LangChain-serialisable object to be revived from attacker-controlled input. Affected API surfaces include RunnableWithMessageHistory, astream_log(), and astream_events(version="v1"), where attacker-supplied nested dictionaries preserved in run inputs or outputs are deserialised without adequate restriction. An attacker who can submit untrusted structured input to an affected application can inject LangChain serialised constructor payloads to instantiate classes with untrusted constructor arguments.