CVE-2021-41124: Splash authentication credentials potentially leaked to target websites in scrapy-splash

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-10-05 · updated 2026-06-17
Weakness: CWE-200

Description

Scrapy-splash is a library which provides Scrapy and JavaScript integration. In affected versions users who use [`HttpAuthMiddleware`](http://doc.scrapy.org/en/latest/topics/downloader-middleware.html#module-scrapy.downloadermiddlewares.httpauth) (i.e. the `http_user` and `http_pass` spider attributes) for Splash authentication will have any non-Splash request expose your credentials to the request target. This includes `robots.txt` requests sent by Scrapy when the `ROBOTSTXT_OBEY` setting is set to `True`. Upgrade to scrapy-splash 0.8.0 and use the new `SPLASH_USER` and `SPLASH_PASS` settings instead to set your Splash authentication credentials safely. If you cannot upgrade, set your Splash request credentials on a per-request basis, [using the `splash_headers` request parameter](https://github.com/scrapy-plugins/scrapy-splash/tree/0.8.x#http-basic-auth), instead of defining them globally using the [`HttpAuthMiddleware`](http://doc.scrapy.org/en/latest/topics/downloader-middleware.html#module-scrapy.downloadermiddlewares.httpauth). Alternatively, make sure all your requests go through Splash. That includes disabling the [robots.txt middleware](https://docs.scrapy.org/en/latest/topics/downloader-middleware.html#topics-dlmw-robots).

Affected products

scrapy-plugins scrapy-splash: before 0.8.0 — fixed in 0.8.0

How to fix

Upgrade to a fixed version: scrapy-plugins scrapy-splash 0.8.0. Check the vendor advisory for mitigations.

References

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