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CVE-2026-42271 CISA KEV high CVSS 8.8

[KEV] OS Command Injection in BerriAI LiteLLM (CVE-2026-42271)

Summary

OS command injection in BerriAI LiteLLM (CVE-2026-42271). Successful exploitation can lead to full system takeover. Exploitable via POST /mcp-rest/test/connection. Listed in CISA KEV — actively exploited. Mitigation: upgrade to 1.83.7 or later.

Original description

The description as published by the source.

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.

Source: NIST National Vulnerability Database NVD GitHub Advisory CISA KEV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-42271 has been found in BerriAI LiteLLM.
Attackers can target a specific entry point like POST /mcp-rest/test/connection over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
Note: CISA has officially confirmed this is actively exploited in the wild. Treat it with elevated urgency.
What to do: upgrade BerriAI LiteLLM to 1.83.7 or later.
If unsure, ask your IT team or search "BerriAI LiteLLM CVE-2026-42271" on the vendor's site.

CVE-2026-42271 (BerriAI LiteLLM) — CWE-78 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /mcp-rest/test/connection / POST /mcp-rest/test/tools/list / command / args
Patched: 1.83.7 — apply immediately
Listed in CISA KEV — actively exploited, treat as top priority.
Workaround: If upgrading is not immediately possible, developers should block POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list at their reverse proxy or API gateway.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

OS command injection (CWE-78) exists in BerriAI LiteLLM. Attackers reach the vulnerable code path via POST /mcp-rest/test/connection.

📍 Affected scope

Check the vendor advisory for the affected versions of BerriAI LiteLLM. Attack surface: POST /mcp-rest/test/connection / POST /mcp-rest/test/tools/list / command / args.

🔥 Severity

Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover. Listed in CISA KEV — actively exploited in the wild, treat as top priority.

🔧 How to fix

Update to 1.83.7.

🛡️ Workaround

Workaround: If upgrading is not immediately possible, developers should block POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list at their reverse proxy or API gateway.

🔍 Detection

Search webserver/proxy logs for unusual POST /mcp-rest/test/connection requests with malformed payloads or SQL meta-characters. Run grep -r 'litellm' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'litellm' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で litellm を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Hunt for indicators of compromise detect 
    grep 'POST /mcp-rest/test/connection' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで POST /mcp-rest/test/connection への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Consider incident declaration escalate 
    Notify SOC / on-call

    CISA KEV登録済 = 実環境で悪用が観測されている。Step 2 で兆候があればインシデント対応宣言、無くてもパッチ適用までWAF強化を最優先で。

  4. 4
    Apply temporary workaround mitigate 
    If upgrading is not immediately possible, developers should block `POST /mcp-rest/test/connection` and `POST /mcp-rest/test/tools/list` at their reverse proxy or API gateway.

    パッチが適用されるまでの応急処置として、If upgrading is not immediately possible, developers should block POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list at their reverse proxy or API gateway. を実施。回避策の副作用 (機能低下) を確認した上で。

  5. 5
    Apply patch patch 
    Upgrade BerriAI LiteLLM to 1.83.7

    ステージング環境で 1.83.7 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。

  6. 6
    Post-deployment verification verify 
    Replay attack against POST /mcp-rest/test/connection on staging to confirm patch closes the vector

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

pip litellm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.83.7"}]}]
PyPI litellm
[{"type":"ECOSYSTEM","events":[{"introduced":"1.74.2"},{"fixed":"1.83.7"}]}]

References

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