CVE-2026-84366 Scrapy: S3DownloadHandler sends signed S3 requests over plaintext HTTP by default
Scrapy sends signed S3 requests over plaintext HTTP by default, allowing attackers to read credentials and data or modify responses via man-in-the-middle attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-84366?
CVE-2026-84366 is a high-severity vulnerability in scrapy, published on 1 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-319
Which versions are affected by CVE-2026-84366?
3 open source packages ship an affected version, including scrapy.
| Package | Affected | Fixed in |
|---|---|---|
scrapy PyPI | All versions | 2.17 |
scrapy PyPI | All versions | 2.17 |
scrapy PyPI | All versions | 2.17.0 |
How do I fix CVE-2026-84366?
Upgrade scrapy to a fixed version for your release line: 2.17 or 2.17.0.
Is CVE-2026-84366 being exploited?
There is no known exploitation of CVE-2026-84366 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-84366, GHSA-76g3-c3x4-crvx, PYSEC-2026-3918, UBUNTU-CVE-2026-84366.