CVE-2026-48121 langchain-ai CVE debrief

Who should care

Defenders of applications using @langchain/langgraph-checkpoint-mongodb versions 1.3.0 and below, especially in multi-tenant or user-isolated setups, should assess exposure and verify input validation and schema enforcement to prevent NoSQL injection attacks.

Why it matters

CVE-2026-48121 is a NoSQL injection vulnerability in @langchain/langgraph-checkpoint-mongodb versions 1.3.0 and below. It allows attackers to bypass thread scoping and leak checkpoints across tenants if untrusted input is not properly validated. Defenders should assess exposure, verify input validation, and consider upgrading to version 1.3.1 or later.

• Potential leakage of checkpoints, including pending writes, across tenants.
• Bypassing of thread scoping due to lack of input validation.
• Possible unauthorized access to sensitive data in multi-tenant environments.
• Need for verification of input validation and schema enforcement in affected applications.

Technical summary

The @langchain/langgraph-checkpoint-mongodb package provides a LangGraph.js CheckpointSaver implementation that uses MongoDB for storage. Versions 1.3.0 and below are vulnerable to NoSQL injection due to lack of type enforcement on checkpoint identifiers passed into MongoDB find() queries. This allows attackers to bypass thread scoping and leak checkpoints, including pending writes, across tenants if untrusted input is forwarded into config.configurable without proper validation.

Defensive priority

Assess exposure in multi-tenant or user-isolated setups using @langchain/langgraph-checkpoint-mongodb versions 1.3.0 and below; verify input validation and schema enforcement.

Recommended defensive actions

• Assess if applications forward untrusted input into config.configurable without coercing it to strings or validating it against a schema.
• Verify input validation and schema enforcement in multi-tenant or user-isolated setups using @langchain/langgraph-checkpoint-mongodb versions 1.3.0 and below.
• Consider upgrading to version 1.3.1 or later.
• Review and update security configurations to prevent NoSQL injection attacks.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the NoSQL injection vulnerability in @langchain/langgraph-checkpoint-mongodb. GitHub references offer additional context. The vulnerability allows attackers to bypass thread scoping and leak checkpoints, including pending writes, across tenants if untrusted input is forwarded into config.configurable without proper validation. Evidence of the vulnerability's existence and impact can be found in the CVE record, NVD entry, and GitHub references. Defenders should verify input validation and

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.