CVE-2026-123817

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-11-06 15:27 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-11-09 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-09 21:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: not scored yet.
• Severity: 8.7 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-11-09 21:17 UTC

Last modified

2026-11-09 21:17 UTC

Weakness

CWE-770 · Allocation without limits

Record status

Received

Affected

• aio-libs Aiohttp < 3.14.4

Attack profile CVSS 4.0 · 8.7

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-123817.md and follow it. Check whether this project is affected by CVE-2026-123817. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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