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BREW-scrapy-CVE-2026-84366 — Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default

Affected: Homebrew: scrapy

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.

CVE-2026-84366 — Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default

Affected: scrapy

GHSA-76g3-c3x4-crvx — Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default

Affected: PyPI: scrapy

### 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`:

```python 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:

```python 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:

```text 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.

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