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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-c427-h43c-vf67 AIOHTTP accepts duplicate Host headers
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 02 Apr 2026 20:30:00 +0000

Type Values Removed Values Added
First Time appeared Aio-libs
Aio-libs aiohttp
Vendors & Products Aio-libs
Aio-libs aiohttp

Thu, 02 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N'}

threat_severity

Moderate


Wed, 01 Apr 2026 23:45:00 +0000

Type Values Removed Values Added
Description 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.
Title AIOHTTP: Duplicate Host header accepted
Weaknesses CWE-20
CWE-444
References
Metrics cvssV4_0

{'score': 6.3, '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-02T16:24:11.311Z

Reserved: 2026-03-30T16:03:31.048Z

Link: CVE-2026-34525

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-01T21:17:00.490

Modified: 2026-04-01T21:17:00.490

Link: CVE-2026-34525

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-01T20:28:46Z

Links: CVE-2026-34525 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-02T20:16:38Z

Weaknesses