Daily Insight: Agentic AI Risk | LangChain Serialization Injection Leaks Environment Secrets

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Assumption Retired:
Agent frameworks inherit trust boundaries from their host environments.

Insight:
LangGrinch (CVE-2025-68664, CVSS up to 9.3 depending on scoring source) collapses that assumption. The issue is serialization injection in dumps()/dumpd() that becomes exploitable when data is later reconstructed via LangChain's load()/loads() paths. Prompt injection can shape structured outputs containing the reserved lc key used to mark serialized objects. When those outputs stream through normal flows (logging, caching, event streaming), the framework treats them as trusted LangChain objects. Environment variables leak. In affected versions, secrets_from_env was enabled by default unless explicitly disabled. Affected: langchain-core versions < 0.3.81 and < 1.2.5. Fixed versions available.

Unresolved Edge:
How many production agent deployments serialize LLM outputs to persistent stores without treating model responses as untrusted input?