MEDIUM5.3

PYSEC-2026-2103

Quick fix

PYSEC-2026-2103 — aiohttp: upgrade to the fixed version with the command below.

pip install --upgrade 'aiohttp>=3.13.4'

Details

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, multiple Host headers were allowed in aiohttp. This issue has been patched in version 3.13.4.

Are you affected?

Enter the version of the package you're using.

Affected packages

PyPI/aiohttp

Introduced in: 0Fixed in: 3.13.4

Fixpip install --upgrade 'aiohttp>=3.13.4'

References

https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4[ADVISORY]
https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000[FIX]
https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349[FIX]
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67[FIX]