CVE-2026-59823 LiteLLM: Server-side request forgery via the `user_config` request parameter in LiteLLM Proxy
Authenticated users can exploit a validation bypass in LiteLLM Proxy to redirect server-side requests to internal or external hosts, potentially exposing restricted endpoints.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59823?
CVE-2026-59823 is a medium-severity server-side request forgery vulnerability in BerriAI litellm, published on 16 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-59823?
3 open source packages ship an affected version, including litellm.
| Package | Affected | Fixed in |
|---|---|---|
litellm PyPI | All versions | 1.83.9 |
litellm PyPI | All versions | 1.83.9 |
litellm PyPI | All versions | 1.83.9 |
How do I fix CVE-2026-59823?
Upgrade litellm to 1.83.9 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-59823 being exploited?
There is no known exploitation of CVE-2026-59823 in the wild and no public exploit code.
Sources
Also known as ECHO-312d-3fe3-ae81, GHSA-hx8v-g79f-8w5f, MINI-9hqf-57ff-x92m, MINI-ggxq-v7j5-3cwv, MINI-j38m-7f5r-pc3g, MINI-pwf2-rf9p-3477 and 3 more.