miguelgrinberg python-engineio up to 4.13.1 allocation of resources

Summaryinfo

A vulnerability categorized as problematic has been discovered in miguelgrinberg python-engineio up to 4.13.1. This vulnerability affects unknown code. Such manipulation leads to allocation of resources. This vulnerability is traded as CVE-2026-48809. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in miguelgrinberg python-engineio up to 4.13.1. Affected by this issue is an unknown functionality. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. CVE summarizes:

python-engineio is a Python implementation of the Engine.IO realtime client and server. Versions prior to 4.13.2 have two specific configurations of the python-engineio server in which the size of incoming messages is not checked before the messages are loaded into memory. An attacker can take advantage of these to cause unnecessary memory allocations in the python-engineio server. The two cases are POST requests, when using ASGI with the long polling transport and WebSocket messages, when using Aiohttp with the WebSocket transport. Version 4.13.2 addresses this issue. ASGI severs now only load the body of incoming requests into memory after the client is confirmed to be known and authenticated, and the payload size is below the maximum allowed size. Requests that do not comply with these requirements are discarded. Aiohttp servers configure the maximum payload size in the underlying WebSocket layer from Aiohttp, so that large messages are discarded by Aiohttp before they are delivered to python-engineio.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-48809 since 05/22/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 4.13.2 eliminates this vulnerability.

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Productinfo

Type

• Programming Language Software

Vendor

• miguelgrinberg

Name

• python-engineio

Version

• 4.13.0
• 4.13.1

Website

• Product: https://github.com/miguelgrinberg/python-engineio/

CPE 2.3info

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CPE 2.2info

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