# 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.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Sep 2026
- **Updated:** 2 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-84366, GHSA-76g3-c3x4-crvx, PYSEC-2026-3918, UBUNTU-CVE-2026-84366

## 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 (Cleartext Transmission of Sensitive Information)

## Which versions are affected by CVE-2026-84366?

3 open source packages ship an affected version, including scrapy.


| Package | Ecosystem | 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84366 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-84366 in the wild and no public exploit code.

Affected packages and fixed versions:
- scrapy (PyPI): affected all versions; fixed in 2.17
- scrapy (PyPI): affected all versions; fixed in 2.17
- scrapy (PyPI): affected all versions; fixed in 2.17.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-84366/ (Markdown: https://insights.sbomify.com/CVE-2026-84366/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84366
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84366
- OSV: https://osv.dev/vulnerability/CVE-2026-84366

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84366/
Summaries are generated and may contain mistakes; the official description above is the record.