CVE-2026-69243 AIOHTTP: HTTP request smuggling via WebSocket upgrade
Attackers can exploit HTTP request smuggling via WebSocket upgrades in aiohttp server, potentially leading to data manipulation or cache poisoning.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-69243?
CVE-2026-69243 is a medium-severity vulnerability in aio-libs aiohttp, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the HTTP parsers were vulnerable to a request smuggling attack relating to WebSocket upgrades. If using the server-side component, an attacker may be able to execute a request smuggling vulnerability using an edge case in the WebSocket upgrade procedure. A WebSocket upgrade request with a body could cause the parser to switch protocols before the complete request body was received, leaving trailing bytes to be handled as upgraded-protocol or pipelined data rather than normal HTTP body data. This issue is fixed in version 3.14.2.
Weakness: CWE-444
Which versions are affected by CVE-2026-69243?
3 open source packages ship an affected version, including aiohttp.
| Package | Affected | Fixed in |
|---|---|---|
aiohttp PyPI | All versions | 3.14.2 |
aiohttp PyPI | All versions | 3.14.2 |
aiohttp PyPI | All versions | 3.14.2 |
How do I fix CVE-2026-69243?
Upgrade aiohttp to 3.14.2 or later.
Is CVE-2026-69243 being exploited?
There is no known exploitation of CVE-2026-69243 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as AZL-94547, CLEANSTART-2026-QH29600, CLSA-2026-1788935722, DEBIAN-CVE-2026-69243, ECHO-4652-b79b-c705, GHSA-mfx4-hv73-q22v and 33 more.