GHSA-F96H-PMFR-66VW

Vulnerability from github – Published: 2024-10-15 18:12 – Updated: 2024-10-15 19:56
VLAI?
Summary
Starlette Denial of service (DoS) via multipart/form-data
Details

Summary

Starlette treats multipart/form-data parts without a filename as text form fields and buffers those in byte strings with no size limit. This allows an attacker to upload arbitrary large form fields and cause Starlette to both slow down significantly due to excessive memory allocations and copy operations, and also consume more and more memory until the server starts swapping and grinds to a halt, or the OS terminates the server process with an OOM error. Uploading multiple such requests in parallel may be enough to render a service practically unusable, even if reasonable request size limits are enforced by a reverse proxy in front of Starlette.

PoC

from starlette.applications import Starlette
from starlette.routing import Route

async def poc(request):
    async with request.form():
        pass

app = Starlette(routes=[
    Route('/', poc, methods=["POST"]),
])

curl http://localhost:8000 -F 'big=</dev/urandom'

Impact

This Denial of service (DoS) vulnerability affects all applications built with Starlette (or FastAPI) accepting form requests.

Severity ?
0.0 (None)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "starlette"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.40.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-47874"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-10-15T18:12:57Z",
    "nvd_published_at": "2024-10-15T16:15:05Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nStarlette treats `multipart/form-data` parts without a `filename` as text form fields and buffers those in byte strings with no size limit. This allows an attacker to upload arbitrary large form fields and cause Starlette to both slow down significantly due to excessive memory allocations and copy operations, and also consume more and more memory until the server starts swapping and grinds to a halt, or the OS terminates the server process with an OOM error. Uploading multiple such requests in parallel may be enough to render a service practically unusable, even if reasonable request size limits are enforced by a reverse proxy in front of Starlette.\n\n### PoC\n\n```python\nfrom starlette.applications import Starlette\nfrom starlette.routing import Route\n\nasync def poc(request):\n    async with request.form():\n        pass\n\napp = Starlette(routes=[\n    Route(\u0027/\u0027, poc, methods=[\"POST\"]),\n])\n```\n\n```sh\ncurl http://localhost:8000 -F \u0027big=\u003c/dev/urandom\u0027\n```\n\n### Impact\nThis Denial of service (DoS) vulnerability affects all applications built with Starlette (or FastAPI) accepting form requests.\n",
  "id": "GHSA-f96h-pmfr-66vw",
  "modified": "2024-10-15T19:56:06Z",
  "published": "2024-10-15T18:12:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/encode/starlette/security/advisories/GHSA-f96h-pmfr-66vw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-47874"
    },
    {
      "type": "WEB",
      "url": "https://github.com/encode/starlette/commit/fd038f3070c302bff17ef7d173dbb0b007617733"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/encode/starlette"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Starlette Denial of service (DoS) via multipart/form-data"
}


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