LangChain serialization injection vulnerability enables secret extraction

Description

A serialization injection vulnerability exists in LangChain JS’s toJSON() method (and subsequently when string-ifying objects using JSON.stringify(). The method did not escape objects with 'lc' keys when serializing free-form data in kwargs. The 'lc' key is used internally by LangChain to mark serialized objects.

Recommendation

Update the langchain package to the latest compatible version. Followings are version details:

• Affected version(s): **< 0.3.37

  >= 1.0.0, < 1.2.3**

• Patched version(s): **0.3.37

  1.2.3**

References

• GHSA-r399-636x-v7f6
• CVE-2025-68665
• CWE-502
• CAPEC-310
• OWASP 2021-A6
• OWASP 2021-A8

Related Issues

• jsdiff has a Denial of Service vulnerability in parsePatch and applyPatch - CVE-2026-24001
• Volto affected by possible DoS by invoking specific URL by anonymous user - CVE-2025-58047
• Elliptic's ECDSA missing check for whether leading bit of r and s is zero - CVE-2024-42460
• Potential DoS when using ContextLines integration (GHSA-r5w7-f542-q2j4) 10 - Vulnerability

Tags:

npm

langchain