File Disclosure Vulnerability in LangChain Framework

CVE-2026-55443

What is CVE-2026-55443?

The LangChain framework, used for building agents and LLM-powered applications, has a vulnerability that allows unauthorized access to files outside the designated root directory. Prior to version 1.3.9, several components within LangChain fail to properly restrict resolved filesystem paths and expand search patterns securely. Specifically, the middleware for file-search agents does not fully validate search patterns, allowing glob patterns and symlinks to point to unintended files. Additionally, path prefix authorization checks are implemented without adequate constraints, potentially permitting access to sibling paths. This flaw can lead to the disclosure of sensitive files when untrusted inputs influence path values or patterns. Users should update to version 1.3.9 or later to mitigate this risk.

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