Database/AI/ML frameworks & serving
LangChain JS: unescaped 'lc' keys let user data be revived as a LangChain object on deserialization
Impact
toJSON() did not escape user-supplied objects that carry an 'lc' key, the marker LangChain uses to tag its own serialized objects. Free-form data placed in kwargs and later round-tripped through JSON.stringify/deserialization is therefore revived as a legitimate LangChain object instead of inert data, so whoever controls that data controls which object type gets constructed. In an agent or serving tier this is model-controlled or end-user-controlled input shaping internal objects - the kind of confusion that leads to unintended tool or loader instantiation. It matters on a GPU fleet because the affected process is usually the orchestrator that holds the provider keys and the tool credentials.
Who can reach it
Anyone who can place free-form data into kwargs that the application serializes and deserializes - typically an end user or an upstream model response. No authentication to the host is needed; authentication depends on the application.
What to do
Upgrade @langchain/core to 0.3.80 or 1.1.8, and langchain to 0.3.37 or 1.2.3, then restart the Node service that embeds them. A dependency bump and a process restart - no node drain, and no firmware or kernel work.
References
Related entries
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This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.