CVE-2021-21330: Aiohttp

Medium severity, CVSS 6.1. EPSS: 1.9% chance of exploitation in the next 30 days.

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. In aiohttp before version 3.7.4 there is an open redirect vulnerability. A maliciously crafted link to an aiohttp-based web-server could redirect the browser to a different website. It is caused by a bug in the `aiohttp.web_middlewares.normalize_path_middleware` middleware. This security problem has been fixed in 3.7.4. Upgrade your dependency using pip as follows "pip install aiohttp >= 3.7.4". If upgrading is not an option for you, a workaround can be to avoid using `aiohttp.web_middlewares.normalize_path_middleware` in your applications.

Affected products

• Aiohttp Aiohttp: before 3.7.4 (fixed in 3.7.4)
• Debian Debian Linux: version 10.0 only
• Fedoraproject Fedora: version 33 only; version 34 only

Published 2021-02-26. Last modified 2026-06-17.