CVE-2026-128129AIOHTTP: Unbounded buffering of data received during an upgrade request

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, aiohttp buffers all additional connection data received while a request marked for upgrade, such as a WebSocket handshake, is being handled, without a size limit or flow control. A remote attacker can stream data behind an upgrade request to a handler that does not immediately accept or reject the upgrade and cause unbounded memory consumption. This issue is fixed in version 3.14.4.

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

References and patches

• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-pw86-h8fm-j323
• https://github.com/aio-libs/aiohttp/pull/13501
• https://github.com/aio-libs/aiohttp/pull/13511
• https://github.com/aio-libs/aiohttp/commit/3d850ee9b92573c7e913821cbcb96005beb3f4df
• https://github.com/aio-libs/aiohttp/commit/c207cadb257e0959b192ffca0548eca8c71eb96a
• https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4