Bug 2573478 (CVE-2026-128129)

Summary: CVE-2026-128129 aiohttp: aiohttp: Denial of Service via unbounded buffering during connection upgrades
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in aiohttp. This vulnerability allows a remote attacker to cause a Denial of Service (DoS) through excessive memory consumption. When handling an HTTP connection upgrade request, such as a WebSocket handshake, incoming data is buffered without size limits or flow control until the request handler completes. By continuously streaming data behind an uncompleted upgrade request, an attacker can exhaust system memory and crash the application.
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Description OSIDB Bzimport 2026-11-13 20:41:53 UTC 
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.