Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default

{
  "id": "59c25662ccb2103b6b283d9c41a4eeebbedc9e0a4ea4aa4fc6fd9ea2840897be",
  "url": "https://osv.dev/vulnerability/CVE-2026-84366",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default",
    "summary": "Scrapy is a high-level web crawling and scraping framework for Python. Prior to 2.17.0, in scrapy/core/downloader/handlers/s3.py, Scrapy's S3DownloadHandler converts an S3-scheme bucket and key request into a plaintext HTTP request to the corresponding S3 endpoint unless request.meta[\"is_secure\"] is explicitly enabled, then signs and sends the plaintext request with configured AWS credentials. A network attacker who can observe traffic between Scrapy and S3 can read the bucket and key path, AWS Authorization header, X-Amz-Security-Token when temporary credentials are used, S3 object contents, and S3 response headers. An active man-in-the-middle attacker can also modify the plaintext S3 response body, status code, and headers before Scrapy processes them, causing scraped-data poisoning, poisoned exports, HTTP cache poisoning when caching is enabled, or influence over later crawl targets through forged redirects or attacker-controlled links. Users making S3-scheme requests with AWS credentials are affected. This issue is fixed in version 2.17.0.",
    "evidence": "osv:CVE-2026-84366",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-84366",
      "aliases": [
        "CVE-2026-84366",
        "GHSA-76g3-c3x4-crvx",
        "PYSEC-2026-3918"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/scrapy/scrapy",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "feb692f552e3ed4533cf4e3af4809908d84cd763"
                },
                {
                  "fixed": "9523e1ec8c41fde265a26d14563d178b6f1ad04b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.17.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "9523e1ec8c41fde265a26d14563d178b6f1ad04b"
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                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "feb692f552e3ed4533cf4e3af4809908d84cd763"
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                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "2.17.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2.16.0",
            "2.15.0",
            "2.14.1",
            "2.14.0",
            "2.13.0",
            "2.12.0",
            "2.11.0",
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            "2.8.0",
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            "0.25.0",
            "0.23.0",
            "0.21.0",
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            "0.14.0",
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            "0.10.3",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84366.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.526449455Z",
      "provider": "osv",
      "references": [
        "https://github.com/scrapy/scrapy/releases/tag/2.17.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84366.json",
        "https://github.com/scrapy/scrapy/security/advisories/GHSA-76g3-c3x4-crvx",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-84366",
        "https://github.com/scrapy/scrapy/commit/9523e1ec8c41fde265a26d14563d178b6f1ad04b"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-319"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84366.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-84366",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518929,
  "published_at": "2026-09-01T20:29:23.143+00:00"
}