Critical Vulnerability in LangChain Core Exposes Secrets and Enables Prompt Injection
In December 2025, a critical vulnerability was disclosed in LangChain Core, a widely used Python package within the LangChain open-source ecosystem. Attackers were able to exploit a flaw in the serialization process, resulting in exposure of sensitive secrets and the ability to manipulate large language model (LLM) responses via prompt injection. The underlying vulnerability allowed threat actors to craft malicious payloads, leading to remote code execution in environments where untrusted input could be serialized, posing major risks to organizations relying on LangChain-powered AI workflows. This supply-chain attack path also opened the door for access to credentials and proprietary data. This incident highlights the expanding threat landscape targeting AI infrastructure and software supply chains. With the surge of enterprise adoption of AI and LLMs, vulnerabilities in core AI frameworks are increasingly attractive to threat actors, underscoring regulatory scrutiny and the need for robust code security practices within open-source dependencies.
Kill Chain
