PyPI/aiohttp CVE-2026-34525: medium, EPSS 0.39%

AIOHTTP accepts duplicate Host headers

Action: Upgrade aiohttp to 3.13.4 or later.

pip install aiohttp==3.13.4

Affected

Fixed versions

Sources

• osv: GHSA-c427-h43c-vf67
• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67
• https://nvd.nist.gov/vuln/detail/CVE-2026-34525
• https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000
• https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349
• https://github.com/aio-libs/aiohttp
• https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4

CVE-2026-34525 · published 2026-04-01T21:49:45Z · modified 2026-09-10T03:51:01.505705751Z · JSON