CVE-2026-106119: @langchain MongoDB

Medium severity, CVSS 6.0. EPSS: 0.5% chance of exploitation in the next 30 days.

LangChain is a framework for building LLM-powered applications. Prior to 1.3.1, MongoDBChatMessageHistory does not enforce the documented string type for an untrusted structured session identifier at runtime, allowing the identifier to be interpreted as a MongoDB query condition rather than as a literal value when multiple users' histories are stored in a shared MongoDB collection. An attacker able to invoke chat-history operations can read, modify, or delete another user's stored conversation. Applications using authenticated, server-controlled string identifiers are not affected. This issue is fixed in version 1.3.1.

Affected products

• @langchain MongoDB: before 1.3.1 (fixed in 1.3.1)
• Langchain-Ai Langchainjs: before 1.5.14 (fixed in 1.5.14)

Published 2026-10-06. Last modified 2026-10-06.