Bug 2573475 (CVE-2026-128128)

Summary: CVE-2026-128128 aiohttp: aiohttp: Denial of Service via integer overflow in WebSocket reader
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in aiohttp. A remote attacker can trigger an integer overflow in the C-based WebSocket reader by sending a crafted sequence of WebSocket message fragments. This flaw allows an attacker to bypass configured message size limits, leading to excessive memory consumption and causing a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-11-13 20:41:42 UTC 
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, the C WebSocket reader adds a declared frame length to the size of an already buffered partial message using signed 64-bit arithmetic. A length near two to the power of 63 can overflow, allowing the max_msg_size check to pass. A remote peer can send a small non-final fragment followed by an oversized message and cause unbounded memory consumption. The Python WebSocket reader is unaffected. This issue is fixed in version 3.14.4.