CVE-2026-59823: BerriAI LiteLLM

Medium severity, CVSS 5.3. EPSS: 0.4% chance of exploitation in the next 30 days.

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.83.9, an authenticated LiteLLM Proxy caller with a valid virtual key can place api_base inside the user_config request body to bypass is_request_body_safe, which blocks top-level api_base and base_url but previously did not inspect or reject user_config. Because user_config constructs the outbound router, the nested destination redirects a server-side request to an internal or external host selected by the caller and can expose endpoints the caller cannot otherwise access. This issue is fixed in version 1.83.9.

Affected products

• BerriAI LiteLLM: before 1.83.9 (fixed in 1.83.9)

Published 2026-09-16. Last modified 2026-09-30.