CVE-2026-34525: CWE-20: Improper Input Validation in aio-libs aiohttp
CVE-2026-34525 is a medium severity vulnerability in the aiohttp asynchronous HTTP client/server framework for Python. Versions prior to 3. 13. 4 allowed multiple Host headers in HTTP requests due to improper input validation. This issue has been addressed and patched in aiohttp version 3. 13. 4.
AI Analysis
Technical Summary
The vulnerability identified as CVE-2026-34525 affects aiohttp versions before 3.13.4. It involves improper input validation (CWE-20) where multiple Host headers were permitted in HTTP requests. This could lead to unexpected behavior in HTTP request processing. The issue has been fixed in version 3.13.4 of aiohttp.
Potential Impact
Allowing multiple Host headers in HTTP requests can cause ambiguity in request handling, potentially leading to security issues such as request smuggling or bypassing access controls. The CVSS 4.0 score of 6.3 indicates a medium severity impact with network attack vector, high attack complexity, and partial impact on integrity and availability. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Users should upgrade aiohttp to version 3.13.4 or later where this vulnerability is patched. No other mitigation steps are indicated or required according to the available information.
CVE-2026-34525: CWE-20: Improper Input Validation in aio-libs aiohttp
Description
CVE-2026-34525 is a medium severity vulnerability in the aiohttp asynchronous HTTP client/server framework for Python. Versions prior to 3. 13. 4 allowed multiple Host headers in HTTP requests due to improper input validation. This issue has been addressed and patched in aiohttp version 3. 13. 4.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability identified as CVE-2026-34525 affects aiohttp versions before 3.13.4. It involves improper input validation (CWE-20) where multiple Host headers were permitted in HTTP requests. This could lead to unexpected behavior in HTTP request processing. The issue has been fixed in version 3.13.4 of aiohttp.
Potential Impact
Allowing multiple Host headers in HTTP requests can cause ambiguity in request handling, potentially leading to security issues such as request smuggling or bypassing access controls. The CVSS 4.0 score of 6.3 indicates a medium severity impact with network attack vector, high attack complexity, and partial impact on integrity and availability. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Users should upgrade aiohttp to version 3.13.4 or later where this vulnerability is patched. No other mitigation steps are indicated or required according to the available information.
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: 4/1/2026, 8:53:18 PM
Last enriched: 4/10/2026, 12:02:15 AM
Last updated: 5/15/2026, 8:08:59 AM
Views: 90
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