python-socketio is a Python implementation of the Socket.IO realtime client and server. The python-socketio server stores binary `EVENT` and `ACK` messages in memory while it waits to receive their binary attachments. Once all the attachments are received, these messages are then processed. Prior to version 5.16.4, an attacker can submit a binary message and intentionally omit sending one or more of its attachments to cause the message along with the partial list of received attachments to stay in memory for a long time. Version 5.16.4 takes the following measures to address this issue: Binary packets are only accepted from authenticated clients and, when a client disconnects, the server checks if there is a partial binary message being held for the client and deletes it.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-5w7q-77mv-v69f python-socketio: Binary attachment accumulation can cause denial of service
Fixes

Solution

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Workaround

No workaround given by the vendor.

History

Thu, 13 Aug 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 13 Aug 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Miguelgrinberg
Miguelgrinberg python-socketio
Vendors & Products Miguelgrinberg
Miguelgrinberg python-socketio

Tue, 11 Aug 2026 19:30:00 +0000

Type Values Removed Values Added
Description python-socketio is a Python implementation of the Socket.IO realtime client and server. The python-socketio server stores binary `EVENT` and `ACK` messages in memory while it waits to receive their binary attachments. Once all the attachments are received, these messages are then processed. Prior to version 5.16.4, an attacker can submit a binary message and intentionally omit sending one or more of its attachments to cause the message along with the partial list of received attachments to stay in memory for a long time. Version 5.16.4 takes the following measures to address this issue: Binary packets are only accepted from authenticated clients and, when a client disconnects, the server checks if there is a partial binary message being held for the client and deletes it.
Title python-socketio: Binary attachment accumulation can cause denial of service
Weaknesses CWE-770
References
Metrics 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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-13T14:39:14.373Z

Reserved: 2026-05-22T20:57:10.975Z

Link: CVE-2026-48804

cve-icon Vulnrichment

Updated: 2026-08-13T14:39:10.596Z

cve-icon NVD

Status : Received

Published: 2026-08-11T20:17:42.580

Modified: 2026-08-13T15:19:41.157

Link: CVE-2026-48804

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-13T09:49:33Z

Weaknesses