CVE-2026-34525 MEDIUM

CVE-2026-34525: AIOHTTP: Duplicate Host header accepted

Vendor Aio-Libs
Product aiohttp
Weakness CWE-20 · Input validation
Published April 1, 2026
Last update April 2, 2026
View on NVD All CVEs

CVSS base score

6.3/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

April 1, 2026 CVE published
April 2, 2026 Record updated