{"action":"Upgrade aiohttp to 3.13.4 or later.","affected":[{"fixed":"3.13.4","introduced":"0"}],"component":"aiohttp","cve_ids":["CVE-2026-34525"],"ecosystem":"PyPI","epss":0.00299,"exploited":false,"fixed_versions":["3.13.4"],"ghsa_id":"GHSA-c427-h43c-vf67","id":"tcs_01M5KGXG74E4H22BAQHZXXY1BH","modified_at":"2026-07-13T07:15:12.738469444Z","published_at":"2026-04-01T21:17:00.490Z","references":["https://osv.dev/vulnerability/PYSEC-2026-2103","https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4","https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000","https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349","https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67"],"severity":{"label":"medium","score":5.3},"sources":[{"source":"osv","source_id":"PYSEC-2026-2103","url":"https://osv.dev/vulnerability/PYSEC-2026-2103"}],"summary":"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."}