Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default
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 headersAn 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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | scrapy | < 2.17 | 2.17 |
References
- 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
- https://github.com/scrapy/scrapy
- https://github.com/scrapy/scrapy/releases/tag/2.17.0
- https://pypi.org/project/scrapy
- https://github.com/advisories/GHSA-76g3-c3x4-crvx
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-319- Platform
- Python (PyPI)
- Package
scrapy- Disclosed
- 02.09.2026
- Updated
- 11.10.2026 15:18
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-3918 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-76g3-c3x4-crvx - CC BY 4.0
Vulnerability history: scrapy
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 14
- First → latest
- 09.2017 09.2026
- Without a fix
- 1
- Exploited in attacks
- 0
Severity breakdown
- High 6
- Medium 8
Disclosures per year
- 2017: 1
- 2018: 0
- 2019: 0
- 2020: 0
- 2021: 1
- 2022: 3
- 2023: 0
- 2024: 6
- 2025: 1
- 2026: 2
-
Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default this entry
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