https://vulnerability.circl.lu/rss/recent/all/10 Most recent entries from all 2026-09-28T09:26:25.299992+00:00 Vulnerability-Lookup info@circl.lu python-feedgen Contains only the most 10 recent entries. https://vulnerability.circl.lu/vuln/cve-2026-34525 CVE-2026-34525 — AIOHTTP: Duplicate Host header accepted 2026-09-28T09:26:25.466949+00:00

Affected: aio-libs aiohttp

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.

 https://vulnerability.circl.lu/vuln/ghsa-c427-h43c-vf67 GHSA-c427-h43c-vf67 — AIOHTTP accepts duplicate Host headers 2026-09-28T09:26:25.467066+00:00

Affected: PyPI: aiohttp

### Summary

Multiple Host headers were allowed in aiohttp.

### Impact

Mostly this doesn't affect aiohttp security itself, but if a reverse proxy is applying security rules depending on the target Host, it is theoretically possible that the proxy and aiohttp could process different host names, possibly resulting in bypassing a security check on the proxy and getting a request processed by aiohttp in a privileged sub app when using `Application.add_domain()`.

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Patch: https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349 Patch: https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000

 https://vulnerability.circl.lu/vuln/pysec-2026-2103 PYSEC-2026-2103 2026-09-28T09:26:25.467138+00:00

Affected: PyPI: aiohttp

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.