The vulnerability stems from the use of the ast.literal_eval function to parse user input, including input from unauthenticated users. This function is known to be unsafe and can be exploited to cause a Denial of Service (DoS) attack. An attacker can send a specially crafted payload to endpoints protected by user_api_key_auth middleware, causing the server to crash with a segmentation fault (SIGSEGV).

An attacker sends a large payload consisting of repeated '()' characters to an endpoint on the litellm server that uses the user_api_key_auth middleware. The server attempts to parse this payload using ast.literal_eval, leading to excessive memory consumption and ultimately causing a segmentation fault, crashing the server.

Users running the litellm server version git 26c03c9 are affected by this vulnerability. This includes any deployment where user input is parsed using ast.literal_eval without proper authentication or input validation.