CVE-2026-123817

AIOHTTP WebSocket frame reassembly permits excessive memory consumption from tiny reads

Published Nov 9, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, the WebSocket reader retains one bytes object for each transport read while reassembling an incomplete frame. A malicious peer can split a frame into many tiny reads so per-object overhead substantially exceeds the payload bytes allowed by max_msg_size. The condition affects a server receiving frames from a malicious client and a client receiving frames from a malicious server, and can cause excessive memory consumption or denial of service. This issue is fixed in version 3.14.4.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-2g87-pp6c-29x5 aiohttp: Multiple instances of excessive or unbounded memory/CPU use
History
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Type Values Removed Values Added
First Time appeared Aio-libs
Aio-libs aiohttp
Vendors & Products Aio-libs
Aio-libs aiohttp
Type Values Removed Values Added
Description AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, the WebSocket reader retains one bytes object for each transport read while reassembling an incomplete frame. A malicious peer can split a frame into many tiny reads so per-object overhead substantially exceeds the payload bytes allowed by max_msg_size. The condition affects a server receiving frames from a malicious client and a client receiving frames from a malicious server, and can cause excessive memory consumption or denial of service. This issue is fixed in version 3.14.4.
Title AIOHTTP WebSocket frame reassembly permits excessive memory consumption from tiny reads
Weaknesses CWE-770
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 9, 2026, 9:17 PM
Reserved
Nov 6, 2026, 3:27 PM
Status
Awaiting Analysis
Published
Nov 9, 2026, 10:18 PM
Modified
Nov 12, 2026, 10:18 PM
Severity
Important
Public date
Nov 9, 2026, 9:17 PM