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[ CVE-2026-111749 · Published 19 Oct 2026 ]

AIOHTTP: Cookie from subdomain can remove Host-Only Scope from existing cookies

CVSS 2.3 EPSS <1%Fix available

[ Description ]Official description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, Host-Only scope on an existing parent-domain cookie can be removed by a subdomain. A user who accesses an untrusted subdomain can consequently have host-only protections stripped from cookies, although impact is limited when applications do not reflect those cookies to a browser. This issue is fixed in version 3.14.4.

[ Fixes ]Fixes and patches

  • aiohttp 3.14.4Fixed version · GitHub Advisories · pip package aiohttp: upgrade to 3.14.4 or later (affected <= 3.14.3)

[ Packages ]Affected open-source packages

[ References ]References