LangChain langgraph-api: Store authorization bypass (CVE-2026-118668)

The LangChain langgraph-api package contains an authorization vulnerability (CVE-2026-118668) affecting deployments that utilize JavaScript or TypeScript custom authentication handlers. If the handler is configured to rewrite namespaces to restrict user access, the runtime fails to correctly apply these modifications. This allows an authenticated user to perform unauthorized read, search, modify, or delete operations on Store data residing in other users' namespaces.

The issue does not affect Python-based handlers or JavaScript/TypeScript handlers that reject (rather than rewrite) unauthorized requests.

Impact

Successful exploitation allows an authenticated user to bypass logical access controls within the LangGraph Store. This results in unauthorized access, modification, or destruction of data belonging to other users. No administrative privileges or user interaction are required to exploit the flaw.

Recommendation

• Upgrade langgraph-api to version 0.15.0 or later immediately.
• For environments unable to patch, modify JavaScript/TypeScript authorization handlers to explicitly reject requests for unauthorized namespaces, rather than relying on internal namespace rewriting.
• Conduct a review of all Store-related authorization logic to ensure requests are rejected upon unauthorized access attempts.