GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

GHSA-76G3-C3X4-CRVX

Vulnerability from github – Published: 2026-09-02 22:50 – Updated: 2026-09-02 22:50
VLAI
Summary
Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default
Details

Problem

Scrapy’s S3DownloadHandler sends signed S3 requests over plaintext HTTP by default.

A normal request like s3://bucket/key is converted into http://bucket.s3.amazonaws.com/key unless request.meta["is_secure"] is explicitly set. The generated request is then signed with configured AWS credentials, so AWS authorization material can be sent without TLS.

Vulnerable code in scrapy/core/downloader/handlers/s3.py:

scheme = "https" if request.meta.get("is_secure") else "http"
url = f"{scheme}://{bucket}.s3.amazonaws.com{path}"

The request is then signed and dispatched:

self._signer.add_auth(awsrequest)
request = request.replace(url=url, headers=awsrequest.headers.items())

Impact

Users making Scrapy s3:// requests with AWS credentials are impacted.

A network attacker able to observe traffic between Scrapy and S3, such as a public Wi-Fi attacker, compromised router, ISP/corporate network observer, or local network attacker using ARP spoofing, can read:

bucket/key path
AWS Authorization header
X-Amz-Security-Token, if temporary credentials are used
S3 object contents
S3 response headers

An active MITM attacker can also modify the plaintext S3 response body, status code, and headers before Scrapy processes it. This can cause scraped data poisoning, poisoned exports, HTTP cache poisoning when cache is enabled, and influence over later crawl targets through forged redirects or attacker-controlled links.

Suggested classification: CWE-319: Cleartext Transmission of Sensitive Information.

PoC

A minimal PoC creates an s3:// request, enables fake AWS settings, captures the request produced by S3DownloadHandler, and prints the rewritten URL and auth headers.

Severity
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 2.17.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "scrapy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.17"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-84366"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-319"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T22:50:44Z",
    "nvd_published_at": "2026-09-01T21:18:47Z",
    "severity": "HIGH"
  },
  "details": "### Problem\n\nScrapy\u2019s `S3DownloadHandler` sends signed S3 requests over plaintext HTTP by default.\n\nA normal request like `s3://bucket/key` is converted into `http://bucket.s3.amazonaws.com/key` unless `request.meta[\"is_secure\"]` is explicitly set. The generated request is then signed with configured AWS credentials, so AWS authorization material can be sent without TLS.\n\nVulnerable code in `scrapy/core/downloader/handlers/s3.py`:\n\n```python\nscheme = \"https\" if request.meta.get(\"is_secure\") else \"http\"\nurl = f\"{scheme}://{bucket}.s3.amazonaws.com{path}\"\n```\n\nThe request is then signed and dispatched:\n\n```python\nself._signer.add_auth(awsrequest)\nrequest = request.replace(url=url, headers=awsrequest.headers.items())\n```\n\n### Impact\n\nUsers making Scrapy `s3://` requests with AWS credentials are impacted.\n\nA network attacker able to observe traffic between Scrapy and S3, such as a public Wi-Fi attacker, compromised router, ISP/corporate network observer, or local network attacker using ARP spoofing, can read:\n\n```text\nbucket/key path\nAWS Authorization header\nX-Amz-Security-Token, if temporary credentials are used\nS3 object contents\nS3 response headers\n```\n\nAn active MITM attacker can also modify the plaintext S3 response body, status code, and headers before Scrapy processes it. This can cause scraped data poisoning, poisoned exports, HTTP cache poisoning when cache is enabled, and influence over later crawl targets through forged redirects or attacker-controlled links.\n\n\nSuggested classification: **CWE-319: Cleartext Transmission of Sensitive Information**.\n\n\n### PoC\n\nA minimal PoC creates an `s3://` request, enables fake AWS settings, captures the request produced by `S3DownloadHandler`, and prints the rewritten URL and auth headers.",
  "id": "GHSA-76g3-c3x4-crvx",
  "modified": "2026-09-02T22:50:44Z",
  "published": "2026-09-02T22:50:44Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/scrapy/scrapy/security/advisories/GHSA-76g3-c3x4-crvx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84366"
    },
    {
      "type": "WEB",
      "url": "https://github.com/scrapy/scrapy/commit/9523e1ec8c41fde265a26d14563d178b6f1ad04b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/scrapy/scrapy"
    },
    {
      "type": "WEB",
      "url": "https://github.com/scrapy/scrapy/releases/tag/2.17.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.