CVE-2026-42271
LiteLLM: Authenticated command execution via MCP stdio test endpoints
- High 8.8
- Exploited: added to CISA KEV 8 Jun 2026
Description
LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.74.2 to before version 1.83.7, two endpoints used to preview an MCP server before saving it — POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list — accepted a full server configuration in the request body, including the command, args, and env fields used by the stdio transport. When called with a stdio configuration, the endpoints attempted to connect, which spawned the supplied command as a subprocess on the proxy host with the privileges of the proxy process. The endpoints were gated only by a valid proxy API key, with no role check. Any authenticated user — including holders of low-privilege internal-user keys — could therefore run arbitrary commands on the host. This issue has been patched in version 1.83.7.
Key facts
- Published
- 8 May 2026
- Last changed
- 15 Jul 2026
- Assigned by
- GitHub_M
- KEV added
- 8 Jun 2026
- KEV fix due
- 22 Jun 2026
- EPSS
- 91.445% likely to be exploited in the next 30 days, higher than 99.816% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: no; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 8.7CVSS 4.0, Highfrom the CNA (GitHub_M)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:N/SA:N - 8.8CVSS 3.1, Highfrom redhat-SADP (ADP container)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| BerriAI | litellm |
|
Timeline
- 8 May 2026 Published
- 8 Jun 2026 CVE-2026-42271 added to CISA KEV
- 8 Jun 2026 Added to the CISA KEV catalogue
Weakness
Practice this bug class
HackZoneLabs has a hands-on lab on OS command injection (CWE-78).