Threat Intelligence Database

LangChain is a framework for building agents and LLM-powered applications. Prior to 1.3.9, several LangChain components that resolve filesystem paths or expand search patterns do not consistently confine the resolved path to the intended root directory. Affected behaviors include: a file-search agent middleware that validates a starting directory but not the search pattern or the resolved target of matched files, so glob patterns and symlinks can reach files outside the configured root; prompt- and chain/agent-configuration loaders that accept path fields and resolve them without confining the result to a trusted base or rejecting symlink targets; and path-prefix authorization checks that compare by string prefix without a path-segment boundary, so a sibling path sharing the prefix is accepted. When these components receive path values, search patterns, or workspace contents influenced by an untrusted source — including an LLM acting on untrusted input — the result can be disclosure of files outside the intended boundary. This vulnerability is fixed in 1.3.9.

LangChain versions prior to 0.3.85 and between 1.0.0a1 and before 1.3.3 contain a deserialization vulnerability. The framework uses overly broad allowlists when deserializing certain runtime inputs, allowing trusted LangChain-serializable objects to be instantiated with untrusted constructor arguments. This can lead to unintended object instantiation during deserialization. The vulnerability is identified as CWE-502 and has a high severity with a CVSS score of 8.