CVE-2025-53643: Aiohttp

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.12.14, the Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request. If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections. Version 3.12.14 contains a patch for this issue.

Affected products

• Aiohttp Aiohttp: before 3.12.14 (fixed in 3.12.14)

Published 2025-07-14. Last modified 2026-06-17.