Listen to this Post
How the CVE Works
The vulnerability in AIOHTTP arises from improper parsing of chunked transfer encoding trailer sections in HTTP requests. When processing malformed requests containing crafted trailer headers, the pure Python parser fails to properly validate boundaries between chunks. This allows attackers to inject hidden requests by manipulating the `Transfer-Encoding: chunked` header combined with specially crafted trailer sections. The flaw enables HTTP request smuggling where a single malicious request can be interpreted as two distinct requests by downstream systems, potentially bypassing security controls.
DailyCVE Form
Platform: AIOHTTP
Version: <3.9.4
Vulnerability: Request Smuggling
Severity: Critical
Date: 2025-07-15
Prediction: Patch by 2025-07-25
What Undercode Say
import aiohttp
async def exploit():
headers = {'Transfer-Encoding': 'chunked'}
data = "0\r\nX-Injected: smuggled\r\n\r\nGET /admin HTTP/1.1\r\n"
async with aiohttp.ClientSession() as session:
await session.post('http://target/', headers=headers, data=data)
How Exploit
Craft HTTP requests with malformed chunked encoding and trailer headers to bypass proxies.
Protection from this CVE
Update to AIOHTTP ≥3.9.4.
Impact
Firewall bypass, cache poisoning, credential hijacking.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
