# 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.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **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, MINI-q2hg-692v-434q, MINI-x3w9-j9p2-h26p, PYSEC-2026-4070

## 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 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-59823?

3 open source packages ship an affected version, including litellm.


| Package | Ecosystem | 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.

## Is CVE-2026-59823 being exploited?

There is no known exploitation of CVE-2026-59823 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-59823 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-59823 in the wild and no public exploit code.

Affected packages and fixed versions:
- litellm (PyPI): affected all versions; fixed in 1.83.9
- litellm (PyPI): affected all versions; fixed in 1.83.9
- litellm (PyPI): affected all versions; fixed in 1.83.9

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-59823/ (Markdown: https://insights.sbomify.com/CVE-2026-59823/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-59823
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-59823
- OSV: https://osv.dev/vulnerability/CVE-2026-59823

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-59823/
Summaries are generated and may contain mistakes; the official description above is the record.