CVE-2026-69244 AIOHTTP: Out-of-bounds heap read in C HTTP response parser error path (malformed chunked response)
A malicious server can trigger an out-of-bounds heap read in the aiohttp client parser, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-69244?
CVE-2026-69244 is a high-severity memory corruption vulnerability in aio-libs aiohttp, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.3, an out-of-bounds heap read could occur in the C response parser while building an error message for a malformed response. An attacker controlled server, or possibly an accidental response, could trigger a DoS in the client. The vulnerable path was error message construction in aiohttp/_http_parser.pyx, where an llhttp error-position pointer was used to build a snippet for malformed chunked responses and malformed request or response bytes at the buffer end. This issue is fixed in version 3.14.3.
Which versions are affected by CVE-2026-69244?
3 open source packages ship an affected version, including aiohttp.
| Package | Affected | Fixed in |
|---|---|---|
aiohttp PyPI | All versions | 3.14.3 |
aiohttp PyPI | All versions | 3.14.3 |
aiohttp PyPI | All versions | 3.14.3 |
How do I fix CVE-2026-69244?
Upgrade aiohttp to 3.14.3 or later.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-69244 being exploited?
There is no known exploitation of CVE-2026-69244 in the wild and no public exploit code.
Sources
Also known as AZL-94553, CLEANSTART-2026-TB06618, CLSA-2026-1788347890, DEBIAN-CVE-2026-69244, ECHO-c0fa-407f-b85b, GHSA-cq5v-8q36-5273 and 30 more.