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Vulnerability record · CVE-2025-68665 · published 23 December 2025

CVE-2025-68665: Langchain.js deserialization of untrusted data vulnerability

Langchain · Langchain.Js

LangChain is a framework for building LLM-powered applications. Prior to @langchain/core versions 0.3.80 and 1.1.8, and prior to langchain versions 0.3.37 and 1.2.3, 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. When user-controlled data contains this key structure, it is treated as a legitimate LangChain object during deserialization rather than plain user data. This issue has been patched in @langchain/core versions 0.3.80 and 1.1.8, and langchain versions 0.3.37 and 1.2.3

9.1 CVSS 3.1 Critical EPSS 0.79% · top 45.4% CWE-502 · Deserialization of untrusted data
9.1CVSS 3.1 base score
0.79%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
5References
17 Jun 2026Last modified by NVD

Description

LangChain is a framework for building LLM-powered applications. Prior to @langchain/core versions 0.3.80 and 1.1.8, and prior to langchain versions 0.3.37 and 1.2.3, 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. When user-controlled data contains this key structure, it is treated as a legitimate LangChain object during deserialization rather than plain user data. This issue has been patched in @langchain/core versions 0.3.80 and 1.1.8, and langchain versions 0.3.37 and 1.2.3

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/langchain-ai/langchainjs/commit/e5063f9c6e9989ea067dfdff39262b9e7b6aba62 Patch
https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcore%401.1.8 Release Notes
https://github.com/langchain-ai/langchainjs/releases/tag/langchain%401.2.3 Release Notes
https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-r399-636x-v7f6 Vendor Advisory
https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-r399-636x-v7f6 Vendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2025-68665), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.