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.

CVSS 4.0

6.3CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS 3.1

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 21% of CVEs (scores of 2026-10-26)

CWEs

CWE-20, CWE-444

Published

2026-04-01

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• aiohttp:aiohttp

Packages (OSV)

References

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

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