CVE-2026-42203

HIGH LAB

LiteLLM: Server-Side Template Injection in /prompts/test endpoint

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-42203. PoCs published by Astianjy.

AI-analyzed exploit summary This repository contains a functional exploit PoC for CVE-2026-42203, demonstrating a Server-Side Template Injection (SSTI) vulnerability in LiteLLM's /prompts/test endpoint. The exploit uses a Jinja2 template injection to execute arbitrary Python code, confirmed via a CEYE callback mechanism.

Description

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.80.5 to before version 1.83.7, the POST /prompts/test endpoint accepted user-supplied prompt templates and rendered them without sandboxing. A crafted template could run arbitrary code inside the LiteLLM Proxy process. The endpoint only checks that the caller presents a valid proxy API key, so any authenticated user could reach it. Depending on how the proxy is deployed, this could expose secrets in the process environment (such as provider API keys or database credentials) and allow commands to be run on the host. This issue has been patched in version 1.83.7.

Exploits (1)

nomisec WORKING POC
by Astianjy · poc
https://github.com/Astianjy/CVE-2026-42203

This repository contains a functional exploit PoC for CVE-2026-42203, demonstrating a Server-Side Template Injection (SSTI) vulnerability in LiteLLM's /prompts/test endpoint. The exploit uses a Jinja2 template injection to execute arbitrary Python code, confirmed via a CEYE callback mechanism.

Classification
Working Poc 95%
Attack Type
Rce
Complexity
Moderate
Reliability
Reliable
Target: LiteLLM (version not specified)
Auth required
Prerequisites: Valid LiteLLM API key · Access to CEYE API for callback verification · Network access to the target LiteLLM instance
devstral-2 · analyzed May 16, 2026 Full analysis →

References (2)

Core 2
Core References

Scores

CVSS v3 8.8
EPSS 0.0006
EPSS Percentile 18.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Lab Environment

COMMUNITY
Community Lab
docker pull litellm/litellm:main-v1.83.3-stable

Details

CWE
CWE-1336
Status published
Products (3)
BerriAI/litellm >= 1.80.5, < 1.83.7
litellm/litellm 1.80.5 - 1.83.7
pypi/litellm 1.80.5 - 1.83.7PyPI
Published May 08, 2026
Tracked Since May 08, 2026