CVE-2026-51883: The knowledge base creation and document upload interfaces in Langchain-Chatchat 0.3.0;0.3.1 is vulnerable to path trave

The knowledge base creation and document upload interfaces in Langchain-Chatchat 0.3.0;0.3.1 is vulnerable to path traversal. An attacker can inject path traversal sequences (such as ..\) into the knowledge_base_name parameter to write knowledge base content to arbitrary locations outside the configured knowledge base root directory.