Vulnerability · Published Jul 14, 2025 · Assigned by GitHub_M
CVE-2025-53643AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections
Low 1.7
In plain English
A low-severity security flaw in aiohttp from aio-libs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-aiohttp | 3.8.4-1+deb12u2 | DEBIAN-CVE-2025-53643 |
| Debian:13 | python-aiohttp | no fix listed | DEBIAN-CVE-2025-53643 |
| Debian:14 | python-aiohttp | 3.12.15-1 | DEBIAN-CVE-2025-53643 |
| PyPI | aiohttp | 3.12.14 | GHSA-9548-qrrj-x5pj |
| PyPI | aiohttp | 3.12.14 | PYSEC-2026-1104 |
| Ubuntu:25.10 | python-aiohttp | no fix listed | UBUNTU-CVE-2025-53643 |
Affected products (as reported)
Weakness: CWE-444 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U