A vulnerability in the LangChainLLM class of the run-llama/llama_index repository, version v0.12.5, allows for a Denial of Service (DoS) attack. The stream_complete method executes the llm using a thread and retrieves the result via the get_response_gen method of the StreamingGeneratorCallbackHandler class. If the thread terminates abnormally before the _llm.predict is executed, there is no exception handling for this case, leading to an infinite loop in the get_response_gen function. This can be triggered by providing an input of an incorrect type, causing the thread to terminate and the process to continue running indefinitely.

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

CWE-755

https://github.com/run-llama/llama_index/commit/d1ecfb77578d089cbe66728f18f635c09aa32a05

https://huntr.com/bounties/a0b638fd-21c6-4ba7-b381-6ab98472a02a