PYSEC-2026-2599

Vulnerability from pysec - Published: 2026-07-13 15:02 - Updated: 2026-07-13 16:04
VLAI
Details

Impact

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.

Patches

Fixed in 1.83.7. Both test endpoints now require the PROXY_ADMIN role, bringing them into line with the save endpoint.

Workarounds

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.

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.7 (High)
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
Impacted products
Name purl
litellm pkg:pypi/litellm
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "litellm",
        "purl": "pkg:pypi/litellm"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.74.2"
            },
            {
              "fixed": "1.83.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.74.12",
        "1.74.14",
        "1.74.15",
        "1.74.15.post1",
        "1.74.15.post2",
        "1.74.2",
        "1.74.3",
        "1.74.3.post1",
        "1.74.3rc1",
        "1.74.3rc2",
        "1.74.3rc3",
        "1.74.4",
        "1.74.4.dev1",
        "1.74.6",
        "1.74.7",
        "1.74.7.post1",
        "1.74.7.post2",
        "1.74.7rc1",
        "1.74.8",
        "1.74.8.dev2",
        "1.74.9",
        "1.74.9.dev1",
        "1.74.9.dev2",
        "1.74.9.post1",
        "1.74.9.post2",
        "1.75.0",
        "1.75.2",
        "1.75.3",
        "1.75.4",
        "1.75.5.post1",
        "1.75.5.post2",
        "1.75.6",
        "1.75.7",
        "1.75.8",
        "1.75.9",
        "1.76.0",
        "1.76.1",
        "1.76.2",
        "1.76.3",
        "1.77.0",
        "1.77.1",
        "1.77.2.post1",
        "1.77.3",
        "1.77.4",
        "1.77.4.dev1",
        "1.77.5",
        "1.77.7",
        "1.78.0",
        "1.78.0rc2",
        "1.78.2",
        "1.78.3",
        "1.78.4",
        "1.78.5",
        "1.78.6",
        "1.78.7",
        "1.79.0",
        "1.79.0.dev1",
        "1.79.0.dev2",
        "1.79.0.dev3",
        "1.79.1",
        "1.79.2",
        "1.79.3",
        "1.79.3.dev8",
        "1.80.0",
        "1.80.10",
        "1.80.11",
        "1.80.12",
        "1.80.13",
        "1.80.15",
        "1.80.16",
        "1.80.17",
        "1.80.5",
        "1.80.6",
        "1.80.7",
        "1.80.8",
        "1.80.9",
        "1.81.0",
        "1.81.1",
        "1.81.10",
        "1.81.11",
        "1.81.12",
        "1.81.13",
        "1.81.14",
        "1.81.15",
        "1.81.16",
        "1.81.3",
        "1.81.4",
        "1.81.5",
        "1.81.6",
        "1.81.7",
        "1.81.8",
        "1.81.9",
        "1.81.9.dev1",
        "1.82.0",
        "1.82.1",
        "1.82.2",
        "1.82.3",
        "1.82.4",
        "1.82.5",
        "1.82.6",
        "1.83.0",
        "1.83.1",
        "1.83.2",
        "1.83.3",
        "1.83.4",
        "1.83.5",
        "1.83.6"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42271",
    "GHSA-v4p8-mg3p-g94g"
  ],
  "details": "### Impact\n\nTwo endpoints used to preview an MCP server before saving it \u2014 `POST /mcp-rest/test/connection` and `POST /mcp-rest/test/tools/list` \u2014 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.\n\nThe endpoints were gated only by a valid proxy API key, with no role check. Any authenticated user \u2014 including holders of low-privilege internal-user keys \u2014 could therefore run arbitrary commands on the host.\n\n### Patches\n\nFixed in **`1.83.7`**. Both test endpoints now require the `PROXY_ADMIN` role, bringing them into line with the save endpoint.\n\n### Workarounds\n\nIf 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.",
  "id": "PYSEC-2026-2599",
  "modified": "2026-07-13T16:04:36.547554Z",
  "published": "2026-07-13T15:02:53.541330Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/BerriAI/litellm/security/advisories/GHSA-v4p8-mg3p-g94g"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42271"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/BerriAI/litellm"
    },
    {
      "type": "WEB",
      "url": "https://github.com/BerriAI/litellm/releases/tag/v1.83.7-stable"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-42271"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/litellm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-v4p8-mg3p-g94g"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "LiteLLM: Authenticated command execution via MCP stdio test endpoints"
}



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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.