CVE-2026-34525: CWE-20: Improper Input Validation in aio-libs aiohttp
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.
AI Analysis
Technical Summary
CVE-2026-34525 describes a vulnerability in the aiohttp asynchronous HTTP client/server framework for Python, where multiple Host headers were permitted in requests prior to version 3.13.4. This improper input validation could lead to inconsistent or unexpected behavior in how HTTP requests are processed. The vulnerability has been fixed in version 3.13.4.
Potential Impact
The vulnerability allows multiple Host headers in HTTP requests, which may cause inconsistent request interpretation or processing issues in affected aiohttp versions. The CVSS 4.0 base score is 6.3 (medium severity), indicating a moderate impact with network attack vector, high attack complexity, and partial impact on integrity and availability.
Mitigation Recommendations
Upgrade aiohttp to version 3.13.4 or later, where this vulnerability has been patched. No other mitigation is indicated.
CVE-2026-34525: CWE-20: Improper Input Validation in aio-libs aiohttp
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.
CVSS v4.0
Score 6.3medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-34525 describes a vulnerability in the aiohttp asynchronous HTTP client/server framework for Python, where multiple Host headers were permitted in requests prior to version 3.13.4. This improper input validation could lead to inconsistent or unexpected behavior in how HTTP requests are processed. The vulnerability has been fixed in version 3.13.4.
Potential Impact
The vulnerability allows multiple Host headers in HTTP requests, which may cause inconsistent request interpretation or processing issues in affected aiohttp versions. The CVSS 4.0 base score is 6.3 (medium severity), indicating a moderate impact with network attack vector, high attack complexity, and partial impact on integrity and availability.
Mitigation Recommendations
Upgrade aiohttp to version 3.13.4 or later, where this vulnerability has been patched. No other mitigation is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-30T16:03:31.048Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 69cd85bee6bfc5ba1df9d445
Added to database: 04/01/2026, 20:53:18 UTC
Last enriched: 06/24/2026, 15:08:56 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 155
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