CVE-2025-53643

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2025-07-14 21:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 09:38 UTC Last updatedMost recent change to the record

Details

Published

2025-07-14 21:15 UTC

Last modified

2026-06-17 09:38 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-444

Record status

Analyzed

Affected

• Aiohttp < 3.12.14

Attack profile CVSS 4.0 · 1.7

Attack vector

Network

Complexity

Low

Attack requirements

Present

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

Low

Availability

None