Improper input validation in Aio-libs Aiohttp

CVE-2026-34525

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

EPSS: 0.002 (36.9th percentile) — read the EPSS interpretation.

Affected products

Aio-libs Aiohttp — versions < 3.13.4

Weakness classification (CWE)

References

https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67 (x_refsource_CONFIRM)
https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000 (x_refsource_MISC)
https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349 (x_refsource_MISC)
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 (x_refsource_MISC)