CVE-2026-42203

Description

### Impact 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. Proxy deployments running an affected version are in scope. ### Patches The issue is fixed in **`1.83.7-stable`**. The fix switches the prompt template renderer to a sandboxed environment that blocks the attributes this attack relies on. LiteLLM recommends upgrading to `1.83.7-stable` or later. ### Workarounds If upgrading is not immediately possible: 1. Block `POST /prompts/test` at your reverse proxy or API gateway. 2. Review and rotate API keys that should not have access to prompt management routes.

How to fix CVE-2026-42203

To remediate CVE-2026-42203, upgrade the affected package to a fixed version below.

• —upgrade to 1.83.7 or later

Is CVE-2026-42203 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• >= 1.80.5, < 1.83.7

CVSS scores

References (4)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-42203
• PATCHgithub.com/BerriAI/litellm
• WEBgithub.com/BerriAI/litellm/releases/tag/v1.83.7-stable
• WEBgithub.com/BerriAI/litellm/security/advisories/GHSA-xqmj-j6mv-4862