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.
Cite this page
CVE-2025-53643. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2025-53643
Use CWE-444, Aiohttp vendor hub and Aiohttp product page to widen CVE-2025-53643 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2026-22815, CVE-2026-34516 and CVE-2026-34515 for nearby disclosures in the same product family.